“We will spend ourselves down to zero within 20 years of the death of the last of Bill and Melinda,” said Suzman in an interview with Fortune. “But we are actually having active discussions in our board about whether we might want to potentially even accelerate that a little bit.”

Headed by Microsoft founder Bill Gates and his former wife, Melinda French Gates, the Gates Foundation had a $67 billion endowment as of 2022, the last time the organization released figures.

Suzman wrote in the Gates Foundation’s annual donor letter, released Thursday, that the foundation has committed to giving away $8.6 billion this year, roughly one-eighth of its endowment. He also urged wealthy individuals to be a bit more generous with their giving, drawing on the example of Chuck Feeney, a billionaire philanthropist who made his fortune off of duty-free sales. Feeney, who died last October, maintained a low profile throughout his life and gave away almost all of his wealth, much of it to public health and humanitarian causes.

“Imagine the possibilities if more donors followed [Feeney’s] lead. What if, alongside a $100 million gift to a highly selective university, they also gave $100 million to set up a system that makes online textbooks free for every college student in the United States, forever? If a donor gave $20 million to an institution searching for a cure for cancer, and $20 million to fund research on malaria, a disease that still kills a child every minute?” wrote Suzman. 

Founded in 2000, the Gates Foundation spends most of its money on grants to small organizations that fight poverty and disease around the world. One of its best-known campaigns has been funding malaria prevention research, which it’s spent over $1 billion on over the past two decades.

Bill Gates and Melinda French Gates, who cochair the board, have been the largest donors—they’ve contributed $59.1 billion as of 2022. (Their combined net worth is at least $133 billion, per Forbes.) Warren Buffett, a close friend of Gates, has also forked over $35.7 billion of his $125 billion fortune.

The Gates Foundation’s focus makes it an anomaly in the philanthropy world, which favors education—and elite education in particular. In 2022, donors gave just over $70 billion to education, largely to colleges and universities, according to GivingUSA’s annual report. That was more than health ($51.08 billion), social benefit organizations ($48.86 billion), or international affairs ($33.71 billion).

“I know that very few people are willing or able to give away all their wealth. But there’s a lot of ground between Feeney’s blockbuster generosity and the current state of giving among the ultrawealthy—and so many opportunities to make an impact,” Suzman wrote.

Suzman noted that giving rates in the U.S. would be higher if there were stronger laws mandating that foundations spend a minimum amount of their endowment per year. 

“In the United States, Canada, and Australia, philanthropic foundations are required to disburse at least 5% of their assets each year. I personally believe this could be higher,” reads the letter. “Though it’s better than the current situation across most of Europe, where foundations face no payout requirements at all.” (Other charity vehicles, like increasingly popular donor-advised funds, have been criticized for having no requirements to actually spend their funds.)

The letter noted that the combined net worth of the world’s 2,640 billionaires is at least $12.2 trillion—more than 20 times as much as the $500 billion in global charitable giving in 2022. Suzman said if every billionaire were to donate just 0.5% of their wealth, the resulting $61 billion would be enough to save the lives of 2 million mothers and babies, reduce greenhouse gas emissions by one gigaton a year and prevent 7 million deaths through vaccination—with almost $50 billion left over.

And noting that the ultrawealthy have come to dominate charitable giving, Suzman stressed the importance of small individual donors in advancing charitable causes. 

“Small donations, taken together, make an enormous impact,” reads the letter. “Today, nearly half the world’s countries participate in Giving Tuesday, a movement that has facilitated more than $13 billion in donations since its creation in 2012.”

Update, Jan. 25, 2024: This story has been updated after an interview with Gates Foundation CEO Mark Suzman.