Mark Zuckerberg and wife Priscilla Chan named top U.S. philanthropists of 2013

WASHINGTON, Feb. 10 (UPI) -- Mark Zuckerberg and his wife's $1 billion gift to the Silicon Valley Community Foundation in 2013 made them the top philanthropists for 2013., accounting for nearly a seventh of charitable donations made last year.

The Chronicle of Philanthropy's annual top 50 donors list showed that this group of donors were far more generous than they were in 2012, donating $7.7 billion, a 4 percent increase. The median donation also rose to $86.1 million, up from $49.6 million in 2012.

The Facebook founder and Chan were the youngest donors, at 29 and 28 years old, respectively, with the median donor age being 72.

Next on the list was George Mitchell, pioneer of the controversial practice of hydraulic fracturing, popularly known as 'fracking.' He donated $750 million after his death last July, which will go toward supporting clean energy, sustainability and also to prevent environmental damage from the technology that he himself created.

Nike co-founder Phil Knight and his wife Penelope gave the Oregon Health & Science University Foundation $500 million for cancer research. But the money came with a rider -- the university will have to raise the same amount by December 2015 or lose the donation. This 'incentivized' donation has put the university in high gear, and it's already lined up 1,600 donors from 43 states and 13 gifts of $1 million or more.

Barely out of his job as the mayor of New York City, Bloomberg came in fourth with a $452 million pledge. His projects include increasing fish populations in Brazil, Chile, and the Philippines and he has started a nonprofit to help mayors and local organization establish volunteer programs.

Notably off the list were Bill and Melinda Gates, as the list compiles only new donations made in the last year and not old commitments or pledges. But they along with Warren Buffet have been credited with encouraging philanthropy with their Giving Pledge campaign, with 19 of the top 50 donors having signed the pledge.

While colleges, foundations and hospitals took in most of the donations, causes for the environment, children, religion and public broadcasting got the least money from donors.

[The Chronicle of Philanthropy] [CNN]