Belgian Queen Mathilde and Dutch Queen Maxima (R) visit Utrecht train station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Danny Gys/Pool 

Belgian Queen Mathilde and Dutch Queen Maxima (R) visit Utrecht train station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Danny Gys/Pool 

Belgian Queen Mathilde greets Dutch Queen Maxima (R) in Utrecht during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Dutch Queen Maxima (L) and Belgian Queen Mathilde visit Utrecht train station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Belgian Queen Mathilde listens to Dutch Queen Maxima (R) as they visit Utrecht train station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Dutch Queen Maxima and Belgian Queen Mathilde (R) visit Utrecht train station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Belgian Queen Mathilde and Dutch Queen Maxima (R) visit Utrecht train station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Belgian Queen Mathilde and Dutch Queen Maxima (R) disembark from a train at Utrecht central station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Belgian Queen Mathilde and Dutch Queen Maxima (R) disembark from a train at Utrecht central station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Belgian Queen Mathilde and Dutch Queen Maxima (R) disembark from a train at Utrecht central station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Dutch Queen Maxima and Belgian Queen Mathilde (R) board a train at Amsterdam central station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Dutch Queen Maxima and Belgian Queen Mathilde (R) board a train at Amsterdam central station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Dutch Queen Maxima and Belgian Queen Mathilde (R) wave as they board a train at Amsterdam central station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Dutch Queen Maxima and Belgian Queen Mathilde (R) wave as they board a train at Amsterdam central station during an official state visit to the Netherlands, November 30, 2016. REUTERS/Denis Closon/Pool 

Belgian Queen Mathilde and Dutch Queen Maxima (R) pose ahead of a concert in Amsterdam during an official state visit to the Netherlands, November 29, 2016. REUTERS/Denis Closon/Pool 

Belgian Queen Mathilde and Dutch Queen Maxima (R) pose ahead of a concert in Amsterdam during an official state visit to the Netherlands, November 29, 2016. REUTERS/Eric Lalmand/Pool 

Belgian King Philippe and Queen Mathilde (1stL) pose with Dutch King Willem-Alexander, Queen Maxima and former Queen Beatrix (R) ahead of a concert in Amsterdam during an official state visit to the Netherlands, November 29, 2016. REUTERS/Denis Closon/Pool 

Belgian King Philippe and Queen Mathilde pose with Dutch King Willem-Alexander and Queen Maxima as they arrive for a concert in Amsterdam during an official state visit to the Netherlands, November 29, 2016. REUTERS/Francois Lenoir 

Belgian King Philippe and Queen Mathilde pose with Dutch King Willem-Alexander and Queen Maxima as they arrive for a concert in Amsterdam during an official state visit to the Netherlands, November 29, 2016. REUTERS/Francois Lenoir 

Belgian Foreign Minister Didier Reynders and Dutch counterpart Bert Koenders (R) sign a border correction treaty as Belgian King Philippe, Dutch King Willem-Alexander and Queen Maxima look on, in Amsterdam during an official state visit to the Netherlands, November 28, 2016. Picture taken November 28, 2016. REUTERS/Didier Lebrun/Pool 

Dutch Queen Maxima (R) and Belgian Queen Mathilde pose with artist Pierre Alechinsky and his wife Michele Dendal (L) as they visit an exhibition at Cobra Museum in Amstelveen during an official state visit to the Netherlands, November 29, 2016. REUTERS/Danny Gys/Pool 

Dutch Queen Maxima (L) and Belgian Queen Mathilde (R) visit an exhibition by artist Pierre Alechinsky at Cobra Museum in Amstelveen during an official state visit to the Netherlands, November 29, 2016. REUTERS/Danny Gys/Pool 

Dutch Queen Maxima (L) and Belgian Queen Mathilde pose as they visit an exhibition by artist Pierre Alechinsky at Cobra Museum in Amstelveen during an official state visit to the Netherlands, November 29, 2016. REUTERS/Danny Gys/Pool 

(L-R) Dutch Queen Maxima and Belgian Queen Mathilde visit an exhibition by artist Pierre Alechinsky at Cobra Museum in Amstelveen during an official state visit to the Netherlands, November 29, 2016. REUTERS/Francois Lenoir 

Belgian Queen Mathilde and Dutch Queen Maxima pose as they visit an exhibition by artist Pierre Alechinsky at Cobra Museum in Amstelveen during an official state visit to the Netherlands, November 29, 2016. REUTERS/Francois Lenoir 

(L-R) Dutch Queen Maxima and Belgian Queen Mathilde visit an exhibition by artist Pierre Alechinsky at Cobra Museum in Amstelveen during an official state visit to the Netherlands, November 29, 2016. REUTERS/Francois Lenoir 

(L-R) Dutch Queen Maxima and Belgian Queen Mathilde visit an exhibition by artist Pierre Alechinsky at Cobra Museum in Amstelveen during an official state visit to the Netherlands, November 29, 2016. REUTERS/Francois Lenoir 

Dutch Queen Maxima and Belgian Queen Mathilde (R) visit a youth centre "Kamers met Kansen" in Amsterdam during an official state visit to the Netherlands, November 29, 2016. REUTERS/Eric Lalmand/Pool 

Dutch Queen Maxima visits a youth centre "Kamers met Kansen" in Amsterdam during an official state visit by Belgian King Philippe and Queen Mathilde to the Netherlands, November 29, 2016. REUTERS/Eric Lalmand/Pool 

Dutch Queen Maxima and Belgian Queen Mathilde (R) visit a youth centre "Kamers met Kansen" in Amsterdam during an official state visit to the Netherlands, November 29, 2016. REUTERS/Eric Lalmand/Pool 

Dutch Queen Maxima and Belgian Queen Mathilde (R) visit a youth centre "Kamers met Kansen" in Amsterdam during an official state visit to the Netherlands, November 29, 2016. REUTERS/Eric Lalmand/Pool 

Dutch Queen Maxima and Belgian Queen Mathilde (R) arrive at a youth centre "Kamers met Kansen" in Amsterdam during an official state visit to the Netherlands, November 29, 2016. REUTERS/Eric Lalmand/Pool 

Dutch Queen Maxima and Belgian Queen Mathilde (R) arrive at a youth centre "Kamers met Kansen" in Amsterdam during an official state visit to the Netherlands, November 29, 2016. REUTERS/Eric Lalmand/Pool 

Belgian Queen Mathilde, Dutch Queen Maxima and King Willem-Alexander (L-R) pose as they arrive at the Binnenhof Square of the Dutch Parliament in The Hague during an official state visit to the Netherlands, November 29, 2016. REUTERS/Francois Lenoir 

Belgian Queen Mathilde, Dutch Queen Maxima and King Willem-Alexander (L-R) pose as they arrive at the Binnenhof Square of the Dutch Parliament in The Hague during an official state visit to the Netherlands, November 29, 2016. REUTERS/Francois Lenoir 

King Willem-Alexander and Queen Maxima of the Netherlands greet well-wishers on arrival at the Shipwreck Galleries during events commemorating the 400th anniversary of the landing of Dutch explorer Dirk Hartog in Western Australia, in Fremantle, Australia, October 31, 2016 REUTERS/Paul Kane/Pool 

King Willem-Alexander and Queen Maxima of the Netherlands greet well-wishers at Victoria Quay during events commemorating the 400th anniversary of the landing of Dutch explorer Dirk Hartog in Western Australia in Fremantle, Australia, October 31, 2016. REUTERS/Paul Kane/POOL 

King Willem-Alexander (L) and Queen Maxima of the Netherlands greet well-wishers on arrival at the Shipwreck Galleries during events commemorating the 400th anniversary of the landing of Dutch explorer Dirk Hartog in Western Australia, in Fremantle, Australia, October 31, 2016 REUTERS/Paul Kane/POOL 

King Willem-Alexander and Queen Maxima of the Netherlands greet well-wishers at Victoria Quay during events commemorating the 400th anniversary of the landing of Dutch explorer Dirk Hartog in Western Australia in Fremantle, Australia, October 31, 2016. REUTERS/Paul Kane/Pool 

King Willem-Alexander and Queen Maxima of the Netherlands visit the Batavia Gallery with Museum director Diana Jones and Curator Michael McCarthy at the Shipwreck Galleries in Fremantle, Australia, on October 31, 2016. REUTERS/Paul Kane/Pool 

King Willem-Alexander and Queen Maxima of the Netherlands visit the Batavia Gallery with Museum director Diana Jones and Curator Michael McCarthy at the Shipwreck Galleries in Fremantle, Australia, on October 31, 2016. REUTERS/Paul Kane/Pool 

Queen Maxima of the Netherlands waves to well-wishers on arrival at the Shipwreck Galleries during events commemorating the 400th anniversary of the landing of Dutch explorer Dirk Hartog in Western Australia, in Fremantle, Australia, October 31, 2016 REUTERS/Paul Kane/Pool 

Queen Maxima of the Netherlands receives a bouquet on arrival at the Shipwreck Galleries during events commemorating the 400th anniversary of the landing of Dutch explorer Dirk Hartog in Western Australia, in Fremantle, Australia, October 31, 2016 REUTERS/Paul Kane/Pool 

Queen Maxima of the Netherlands carries a bouquet on arrival at the Shipwreck Galleries during events commemorating the 400th anniversary of the landing of Dutch explorer Dirk Hartog in Western Australia, in Fremantle, Australia, October 31, 2016 REUTERS/Paul Kane/Pool 

Netherlands' Queen Maxima attends a news conference after a private meeting with Argentine President Mauricio Macri at the Olivos presidential residence in Buenos Aires, Argentina October 12, 2016. REUTERS/Enrique Marcarian 

Netherlands' Queen Maxima attends a news conference after a private meeting with Argentine President Mauricio Macri at the Olivos presidential residence in Buenos Aires, Argentina October 12, 2016. REUTERS/Enrique Marcarian 

Netherlands' Queen Maxima attends a news conference after a private meeting with Argentine President Mauricio Macri at the Olivos presidential residence in Buenos Aires, Argentina October 12, 2016. REUTERS/Enrique Marcarian 

Netherlands' Queen Maxima attends a news conference after a private meeting with Argentine President Mauricio Macri at the Olivos presidential residence in Buenos Aires, Argentina October 12, 2016. REUTERS/Enrique Marcarian 

Netherlands' Queen Maxima arrives for a news conference after a private meeting with Argentine President Mauricio Macri at the Olivos presidential residence in Buenos Aires, Argentina October 12, 2016. REUTERS/Enrique Marcarian 

Netherlands' Queen Maxima laughs as she attends a news conference at the Olivos presidential residence in Buenos Aires, Argentina October 12, 2016. REUTERS/Enrique Marcarian 

King Willem Alexander and Queen Maxima of the Netherlands pose as they visit the Alte Pinakothek hosting Dutch masterpieces from the 17th century in Munich, southern Germany, April 13, 2016. REUTERS/Sven Hoppe/Pool 

King Willem Alexander and Queen Maxima of the Netherlands pose as they visit the Alte Pinakothek hosting Dutch masterpieces from the 17th century in Munich, southern Germany, April 13, 2016. REUTERS/Sven Hoppe/Pool 

King Willem Alexander and Queen Maxima of the Netherlands listen to curator Bernd Ebert (L) as they visit the Alte Pinakothek hosting Dutch masterpieces from the 17th century in Munich, southern Germany, April 13, 2016. REUTERS/Pool

King Willem Alexander and Queen Maxima of the Netherlands listen to curator Bernd Ebert (L) as they visit the Alte Pinakothek hosting Dutch masterpieces from the 17th century in Munich, Germany, April 13, 2016. REUTERS/Sven Hoppe/Pool 

French President Francois Hollande (C) welcomes Dutch King Willem-Alexander (R) and Queen Maxima at the Elysee palace for a dinner in Paris, France, March 10, 2016. REUTERS/Philippe Wojazer TPX IMAGES OF THE DAY

French National Assembly speaker Claude Bartolone (R) poses with King Willem-Alexander (C) and Queen Maxima (L) of the Netherlands during a meeting at the Hotel de Lassay in Paris, France, as part of their State visit to France, March 10, 2016. REUTERS/Charles Platiau

King Willem-Alexander (L) and Queen Maxima of the Netherlands pose upon their arrival at the Hotel de Lassay in Paris, France, as part of their State visit to France, March 10, 2016. REUTERS/Charles Platiau

King Willem-Alexander (L) and Queen Maxima of the Netherlands pose upon their arrival at the Hotel de Lassay in Paris, France, as part of their State visit to France, March 10, 2016. REUTERS/Charles Platiau

French National Assembly speaker Claude Bartolone (L) greets King Willem-Alexander (C) and Queen Maxima of the Netherlands as they arrive at Hotel de Lassay in Paris, France, as part of their State visit to France, March 10, 2016. REUTERS/Charles Platiau

French National Assembly speaker Claude Bartolone (R) greets King Willem-Alexander (C) and Queen Maxima of the Netherlands as they arrive at Hotel de Lassay in Paris, France, as part of their State visit to France, March 10, 2016. REUTERS/Charles Platiau