This is your alma mater calling. Just a friendly reminder not to forget us on your holiday gift list. This year, try to be more like Fred Eshelman.

The pharmaceuticals mogul and 1972 alumnus of the University of North Carolina-Chapel Hill pledged $100 million to the Tar Heels this month, the largest individual gift in the school’s 225-year history.

That’s the spirit of generosity that’s rebuilding endowments at U.S. philanthropies closer to pre-recession levels. Donations climbed 3 percent last year to $335.2 billion after adjusting for inflation, just short of a record, with almost all of the increase coming from individuals, couples and estates, according to the latest figures from the Chicago-based Giving USA Foundation.

Just one cause for concern: The gains have been uneven, skewed toward groups favored by the upper-income households that benefited most from the rebound in stocks and housing. Groups connected to higher education, medical research, and cultural institutions are flush, while growth for those such as the Salvation Army and United Way that rely on smaller individual gifts is lagging behind.

“The favored charities of the wealthy are gaining in share in the philanthropic economy,” a trend that is symptomatic of wealth inequality, said Rob Reich, associate professor of political science at Stanford University in California. “The total amount of money given away by the very wealthy is going up, not because they’re giving away a greater share of their income,” he said, but because “their total income and wealth itself has grown.”

Bigger Gifts

Donations as a percentage of GDP have held near 2 percent since the 1990s, with the annual record reaching $349.5 billion in 2007, according to data from Giving USA, a public-service initiative that monitors charitable activity.

The boost in individual giving last year came from gifts of $80 million or more, indicating that the wealthy’s total share of the philanthropic pie has expanded.

“The gains and losses in giving are increasingly driven by a smaller percentage of the population,” said Patrick Rooney, associate dean for academic affairs and research at the Indiana University Lilly Family School of Philanthropy in Indianapolis, which wrote the report.

The value of itemized contributions reported to the Internal Revenue Service rose 25 percent among households earning $200,000 or more in 2012 from a year earlier, the latest data from the National Center for Charitable Statistics showed. Those making less than $100,000 all saw little change or declines of as much as 6.1 percent among sub-$25,000 households.