Michel Euler, file, Associated Press
Microsoft founder Bill Gates and his spouse Melinda Gates walk through the main lobby at the World Economic Forum in Davos, Switzerland, Jan. 29, 2010.

Maybe the rich were just feeling more generous in 2011.

In a year when billionaire Warren Buffet asked to pay more in taxes, charitable donations from some of the richest in the United States increased.

The ten biggest donations in 2011 were double the size of those made in 2010, reports the Chronicle of Philanthropy. In 2011 the rich gave $2.6 billion compared to $1.3 billion in 2010.

The largest donations included $800 million from the Walton Family (owners of Wal-Mart) for the Crystal Bridges Museum of American Art in Arkansas; $350 million to Cornell University in New York from Charles Feeney, a successful graduate of the school who thought up the idea of duty-free shops in airports; and $225 million to the University of Pennsylvania's School of Medicine from Raymond and Ruth Perelman, who upped their donation from 2005 by $200 million.

The year's biggest giving was still lower than the $2.7 billion given in 2009 and not even close to the $8 billion given in 2008.

The Chronicle of Philanthropy notes that two of the people who made the biggest gifts of the year are among the 69 people who have signed Warren Buffet and Bill and Melinda Gates' "Giving Pledge" to give at least half of their wealth to charities before they die.

Potential changes to the tax code may change wealthy giving behavior next year, leading to a short-term burst of donations, The Chronicle of Philanthropy reported. President Barack Obama has suggested a limit on charitable deductions, which might incentivize the wealthy to accelerate giving before the limit comes into effect in 2013. Also, because of changes in the estate tax, much more of a person's estate may be taxed at death in 2013. According to consultants, more donors are creating charitable lead trusts that pay a charity for years before returning the balance to the donor's heirs.

Not only the rich gave more this year. In 2011 the United States was ranked the top giver in the world, according to the UK-based Charities Aid Foundation. Seventy-three percent of Americans reportedly gave to charity.