Indonesia's Finance Minister Sri Mulyani Indrawati (L) and Co-Chair of the Bill and Melinda Gates Foundation Melinda Gates attend a seminar at the International Monetary Fund - World Bank Annual Meeting 2018 in Nusa Dua, Bali, Indonesia, October 11, 2018. REUTERS/Johannes P. Christo 

World Bank President Jim Yong Kim (L) and Bill Gates, co-chair of the Bill & Melinda Gates Foundation, attend a panel discussion on Building Human Capital during the IMF/World Bank spring meeting in Washington, U.S., April 21, 2018. REUTERS/Yuri Gripas 

World Bank President Jim Yong Kim (L), Bill Gates, co-chair of the Bill & Melinda Gates Foundation and British Secretary of State for International Development Penny Mordaunt pose before a panel discussion on Building Human Capital during the IMF/World Bank spring meeting in Washington, U.S., April 21, 2018. REUTERS/Yuri Gripas 

Bill Gates, co-chair of the Bill & Melinda Gates Foundation, speaks at a panel discussion on Building Human Capital during the IMF/World Bank spring meeting in Washington, U.S., April 21, 2018. REUTERS/Yuri Gripas 

Bill Gates, co-chair of the Bill & Melinda Gates Foundation; speaks at a panel discussion on Building Human Capital during the IMF/World Bank spring meeting in Washington, U.S., April 21, 2018. REUTERS/Yuri Gripas 

Bill Gates, co-chair of the Bill & Melinda Gates Foundation; speaks at a panel discussion on Building Human Capital during the IMF/World Bank spring meeting in Washington, U.S., April 21, 2018. REUTERS/Yuri Gripas 

Bill Gates, co-chair of the Bill & Melinda Gates Foundation; speaks at a panel discussion on Building Human Capital during the IMF/World Bank spring meeting in Washington, U.S., April 21, 2018. REUTERS/Yuri Gripas 

Members of the audience listen to Bill Gates, co-chair of the Bill & Melinda Gates Foundation; at a panel discussion on Building Human Capital during the IMF/World Bank spring meeting in Washington, U.S., April 21, 2018. REUTERS/Yuri Gripas 

Bill Gates, co-chair of the Bill & Melinda Gates Foundation; attends a panel discussion on Building Human Capital during the IMF/World Bank spring meeting in Washington, U.S., April 21, 2018. REUTERS/Yuri Gripas 

Bill Gates, co-chair of the Bill & Melinda Gates Foundation; speaks next to World Bank President Jim Yong Kim at a panel discussion on Building Human Capital during the IMF/World Bank spring meeting in Washington, U.S., April 21, 2018. REUTERS/Yuri Gripas 

Bill Gates, co-chair of the Bill & Melinda Gates Foundation; attends a panel discussion on Building Human Capital during the IMF/World Bank spring meeting in Washington, U.S., April 21, 2018. REUTERS/Yuri Gripas 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation arrives to attend the Commonwealth Business Forum Banquet at the Guildhall in London, Britain April 17, 2018. REUTERS/Simon Dawson 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation arrives to attend the Commonwealth Business Forum Banquet at the Guildhall in London, Britain April 17, 2018. REUTERS/Simon Dawson 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation arrives to attend the Commonwealth Business Forum Banquet at the Guildhall in London, Britain April 17, 2018. REUTERS/Simon Dawson 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation arrives to attend the Commonwealth Business Forum Banquet at the Guildhall in London, Britain April 17, 2018. REUTERS/Simon Dawson 

French President Emmanuel Macron (L) accompanies Bill Gates (R), Co-Chair of Bill & Melinda Gates Foundation, and his wife Melinda as they leave after talks at the Elysee Palace in Paris, France, April 16, 2018. REUTERS/Charles Platiau 

French President Emmanuel Macron (L) accompanies Bill Gates, Co-Chair of Bill & Melinda Gates Foundation as he leaves after talks at the Elysee Palace in Paris, France, April 16, 2018. REUTERS/Charles Platiau 

French President Emmanuel Macron (L) accompanies Bill Gates, Co-Chair of Bill & Melinda Gates Foundation as he leaves after talks at the Elysee Palace in Paris, France, April 16, 2018. REUTERS/Charles Platiau 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation leaves the Elysee Palace in Paris, France, April 16, 2018. REUTERS/Charles Platiau 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation arrives at the Elysee Palace in Paris, France, April 16, 2018. REUTERS/Charles Platiau 

Microsoft founder and billionaire philanthropist Bill Gates (2ndL) and his wife Melinda Gates (2ndR) attend a meeting with French President (unseen) at the Elysee Palace in Paris, France, April 16, 2018. Lionel Bonaventure/Pool via Reuters 

Microsoft founder and billionaire philanthropist Bill Gates (L) and his wife Melinda Gates (2ndR) attend a meeting with French President (unseen) at the Elysee Palace in Paris, France, April 16, 2018. Lionel Bonaventure/Pool via Reuters 

French President Emmanuel Macron (C-background) attends a meeting with Microsoft founder and billionaire philanthropist Bill Gates (C-front) and his wife Melinda Gates (L) at the Elysee Palace in Paris, France, April 16, 2018. Lionel Bonaventure/Pool via Reuters 

French President Emmanuel Macron (C-background) attends a meeting with Microsoft founder and billionaire philanthropist Bill Gates (C-front) and his wife Melinda Gates (L) at the Elysee Palace in Paris, France, April 16, 2018. Lionel Bonaventure/Pool via Reuters 

French President Emmanuel Macron (R) attends a meeting with Microsoft founder and billionaire philanthropist Bill Gates (2ndLL) and his wife Melinda Gates (3rdL) at the Elysee Palace in Paris, France, April 16, 2018. Lionel Bonaventure/Pool via Reuters 

French President Emmanuel Macron (R) attends a meeting with Microsoft founder and billionaire philanthropist Bill Gates (L) and his wife Melinda Gates (2ndL) at the Elysee Palace in Paris, France, April 16, 2018. Lionel Bonaventure/Pool via Reuters 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation, arrives at the Elysee Palace in Paris, France, April 16, 2018. REUTERS/Charles Platiau 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation, gestures as he speaks during the World Economic Forum (WEF) annual meeting in Davos, Switzerland January 25, 2018. REUTERS/Denis Balibouse 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation, gestures as he speaks during the World Economic Forum (WEF) annual meeting in Davos, Switzerland January 25, 2018. REUTERS/Denis Balibouse 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation, gestures as he speaks during the World Economic Forum (WEF) annual meeting in Davos, Switzerland January 25, 2018. REUTERS/Denis Balibouse 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation, gestures as he speaks during the World Economic Forum (WEF) annual meeting in Davos, Switzerland January 25, 2018. REUTERS/Denis Balibouse 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation, attends the World Economic Forum (WEF) annual meeting in Davos, Switzerland January 25, 2018. REUTERS/Denis Balibouse 

Bill Gates, Co-Chair of Bill & Melinda Gates Foundation, attends the World Economic Forum (WEF) annual meeting in Davos, Switzerland January 25, 2018. REUTERS/Denis Balibouse 

U.S. Secretary of State Rex Tillerson delivers a keynote address at the 13th Annual Grand Challenges Meeting co-hosted by the Bill & Melinda Gates Foundation in Washington, U.S., October 4 2017. REUTERS/Yuri Gripas 

U.S. Secretary of State Rex Tillerson delivers a keynote address at the 13th Annual Grand Challenges Meeting co-hosted by the Bill & Melinda Gates Foundation in Washington, U.S., October 4 2017. REUTERS/Yuri Gripas 

U.S. Secretary of State Rex Tillerson leaves after delivering remarks at the 13th Annual Grand Challenges Meeting co-hosted by the Bill & Melinda Gates Foundation in Washington, U.S., October 4 2017. REUTERS/Yuri Gripas 

U.S. Secretary of State Rex Tillerson leaves after delivering remarks at the 13th Annual Grand Challenges Meeting co-hosted by the Bill & Melinda Gates Foundation in Washington, U.S., October 4 2017. REUTERS/Yuri Gripas 

U.S. Secretary of State Rex Tillerson prepares to leave after delivering remarks at the 13th Annual Grand Challenges Meeting co-hosted by the Bill & Melinda Gates Foundation in Washington, U.S., October 4 2017. REUTERS/Yuri Gripas 

U.S. Secretary of State Rex Tillerson waves at the 13th Annual Grand Challenges Meeting co-hosted by the Bill & Melinda Gates Foundation in Washington, U.S., October 4 2017. REUTERS/Yuri Gripas 

U.S. Secretary of State Rex Tillerson waves at the 13th Annual Grand Challenges Meeting co-hosted by the Bill & Melinda Gates Foundation in Washington, U.S., October 4 2017. REUTERS/Yuri Gripas 

U.S. Secretary of State Rex Tillerson delivers a keynote address at the 13th Annual Grand Challenges Meeting co-hosted by the Bill & Melinda Gates Foundation in Washington, U.S., October 4 2017. REUTERS/Yuri Gripas 

U.S. Secretary of State Rex Tillerson delivers a keynote address at the 13th Annual Grand Challenges Meeting co-hosted by the Bill & Melinda Gates Foundation in Washington, U.S., October 4 2017. REUTERS/Yuri Gripas 

U.S. Secretary of State Rex Tillerson arrives at the 13th Annual Grand Challenges Meeting co-hosted by the Bill & Melinda Gates Foundation in Washington, U.S., October 4 2017. REUTERS/Yuri Gripas 

Jerome Jarre, Juanpa Zurita, and Casey Neistat speak at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Raj Panjabi speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Stephen Fry speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Stephen Fry speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Queen Maxima of the Netherlands speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Stephen Fry and Isha Sesay speak at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Astro Teller speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Vittorio Colao speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Susan Desmond-Hellmann speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Trevor Noah speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Tom Ellman speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

George the Poet speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Nicholas Kristof speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Isha Sesay speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Bill Gates speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Leymah Gbowee speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff 

Will.i.am speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York, U.S., September 20, 2017. REUTERS/Elizabeth Shafiroff