As world leaders gather at the World Economic Forum in Davos this week, Forbes and Global Citizen have partnered up to unveil a list of the Top 25 Givers between 2014 and 2018.

The new list, compiled by Forbes and announced on Tuesday, has named the biggest philanthropists in America in recent years.

It's been released in conjunction with Global Citizen’s Give While You Live campaign, also announced on Tuesday, which calls for the world’s 2,150 billionaires to join the mission to end extreme poverty by 2030.

We’re urging the world’s billionaires to donate 5% of their wealth each year to the effort to achieve the Global Goals in the next 10 years. Together, these billionaires are worth $10 trillion — which is 30 times the funding needed annually to end extreme poverty ($350 billion).

You can find out all about the Give While You Live campaign, and how you can get involved, here.

The new Forbes list is different, because it ranks the donors based on how much of their money actually reaches the people who need it, as opposed to being pledged to the billionaire’s own charitable foundations.

Private charitable foundations can be a problem, because the money pledged to them will often not be used for years — and the world urgently needs funding to end extreme poverty now.

Warren Buffett takes the top spot on the Forbes list, as the biggest philanthropist of the past five years having given away $14.7 billion dollars (16% of his current net worth). He’s followed by Bill and Melinda Gates, who have given away $9.9 billion (9% of their net worth).

The list also includes how much the philanthropists have given, as a percentage of their net worth. On that ranking, Duty Free Shoppers’ Chuck Feeney comes out way on top, having given away practically all of his fortune on his mission to "die broke."

At the other end of the spectrum, meanwhile, is Facebook co-founder Mark Zuckerberg and his wife Priscilla Chan, and Nike co-founder Phil Knight, both of whom have given away less than 2% of their net worth.

Here’s a brief introduction to the top 10 philanthropists — including the sustainable development issues that they care about most.

1. Warren Buffett

American business magnate Buffett has given away $14.7 billion (16.3% of his current net worth) in the past five years, particularly focusing on health and poverty alleviation — channelling a lot of donations into the Bill & Melinda Gates Foundation.

2. Bill & Melinda Gates

The co-founders of the Bill & Melinda Gates Foundation — the world's largest private charitable foundation — have given away $9.9 billion (9% of their net worth) to support causes such as economic development, health care, and education. According to Forbes, the Gates Foundation has distributed $50 billion in grants since 1994.

3. George Soros

One of the most generous donors in terms of his net worth, the Hungarian-American investor has given 37.4% of his wealth — totaling $3.1 billion — to promote human rights and economic development in Eastern Europe through his Open Society Foundations.

4. Michael Bloomberg

The businessman and former New York City mayor has given $3 billion dollars, or 5% of his net worth, to help promote public health and gun control, as well as to combat climate change.

5. Walton Family

The Walton Family Foundation was launched by Walmart founder Sam Walton and his wife Helen. In the past five years, they've spent a 1.3% of their net worth — spending $2.3 billion — primarily funding efforts such as the building of charter schools, and backing new schooling and testing models. 

6. Jim & Marilyn Simons

The former math professor and his wife have given $1.65 billion in five years — 7.6% of their net worth — to help promote education in the fields of science and math, as well as funding life science research and research into autism.

7. Chuck Feeney

The co-founder of Duty Free Shoppers has said he aims to give away his entire fortune and die broke. He has given away $1.6 billion over the past five years through his foundation Atlantic Philanthropies, which is set to cease operations in 2020. Some of its final initiatives include efforts at promoting health equity throughout the world, and an initiative to reduce the impact of dementia worldwide.

8. Hansjoerg Wyss

Wyss has given aaway $1.55 billion — 24.6% of his net worth — to conservation issues, including pledging to donate $1 billion to protect 30% of the Earth’s surface by 2030. 

9. Pierre Omidyar

The Ebay co-founder has spent $1.4 billion — 10.5% of his net worth — on poverty relief and improved access to education in Africa, India, and Latin America, as well as disaster relief and refugee assistance. 

10. Gordon & Betty Moore

The Intel co-founder and his wife have donated $1.5 billion — 11.9% of their net worth — to causes such as environmental conservation in California, scientific research, and higher education.

These are the philanthropists that also made the list, and how much they've given in the past five years.

11. John & Laura Arnold

5-Year Total: $1.2 billion

Net Worth: $3.3 billion

Percentage of Net Worth Given: 36.4%

12. Mark Zuckerberg & Priscilla Chan

5-Year Total: $1 billion

Net Worth: $81.8 billion

Percentage of Net Worth Given: 1.2%

13. Julian Robertson Jr.

5-Year Total: $881 million

Net Worth: $4.4 billion

Percentage of Net Worth Given: 20%

14. Eli & Edythe Broad

5-Year Total: $816 million

Net Worth: $6.8 billion

Percentage of Net Worth Given: 12%

15. Charles Koch

5-Year Total: $797 million

Net Worth: $42.8 billion

Percentage of Net Worth Given: 1.9%

16. Paul Allen

5-Year Total: $720 million

Net Worth: $20.3 billion

Percentage of Net Worth Given: 3.6%

17. Lynn & Stacy Schusterman

5-Year Total: $713 million

Net Worth: $3.4 billion

Percentage of Net Worth Given: 21%

18. Dustin Moskovitz & Carrie Tuna

5-Year Total: $705 million

Net Worth: $13.5 billion

Percentage of Net Worth Given: 5.2%

19. Ken Griffin

5-Year Total: $620 million

Net Worth: $13.1 billion

Percentage of Net Worth Given: 4.7%

20. Michael & Susan Dell

5-Year Total: $614 million

Net Worth: $31.5 billion

Percentage of Net Worth Given: 2%

21. Bernard & Billi Marcus

5-Year Total: $588 million

Net Worth: $6.4 billion

Percentage of Net Worth Given: 9.2%

22. Ray & Barbara Dalio

5-Year Total: $576 million

Net Worth: $18.7 billion

Percentage of Net Worth Given: 3.1%

23. W. Barron Hilton

5-Year Total: $545 million

Net Worth: n/a

24. Phil Knight

5-Year Total: $533 million

Net Worth: $41 billion

Percentage of Net Worth Given: 1.3%

25. DeVos Family

5-Year Total: $529 million

Net Worth: n/a

Disclosure: Bill Gates is the co-founder of the Bill and Melinda Gates Foundation, a funding partner of Global Citizen.

Editor's note: This piece has been updated to include a disclosure that the Bill and Melinda Gates Foundation is a funding partner of Global Citizen. We regret the oversight.