Stanford University beat Harvard University once again in annual donations as U.S. universities raised a record $40.3 billion, bolstered by at least eight gifts of $100 million or more including art and rare books.

In the year through June 30, Stanford led with $1.63 billion, a record for an individual school, according to a survey of 273 institutions released Wednesday by the New York- based Council for Aid to Education, which tracks university giving. Harvard ranked second with $1.1 billion.

The gifts show that the nation’s wealthiest colleges continue to attract a disproportionate share of higher education philanthropy. The top 20 fundraising schools accounted for 28.7 percent of the total donations. The eight gifts of $100 million or more were received by just four schools, with four going to Stanford and two to Northwestern University. Total charitable contributions rose 7.6 percent while the Standard & Poor’s 500- Stock Index gained 4.6 percent.

“Donors want to be confident that the institution to which they transfer such assets can steward them effectively,” Ann Kaplan, the survey’s director, said in an e-mail. “That means an institution that receives gifts to the endowment must have a track record of good returns on endowment assets.”

Two branches of a family from the Bay Area donated an art collection to Stanford, valued at more than $600 million. The 121 artworks include paintings by Frank Stella, Mark Rothko and Willem de Kooning, and are displayed at a gallery on the Stanford campus that opened in 2014.

The survey said Stanford also received two donations in the fiscal year of $100 million and $106 million, which support activities in the medical center, including two hospitals and its school of medicine, according to the school.

“Increasingly people are looking to the research university in this country to help resolve some of the intractable problems that are facing human kind,” Martin Shell, who oversees Stanford’s fundraising, said in a phone interview. “Universities are seen as positive agents of change and people want to be part of that.”

The school, with an endowment of $22.2 billion as of August 2015, has topped the list for the past decade, with the exception of the year ended June 2014, according to the survey. That’s when Harvard led with $1.16 billion, setting a record at the time for the most raised in a single year.

Books, Manuscripts

Northwestern’s gifts for fiscal 2015 included $100 million from Roberta Buffett Elliott, sister of Warren Buffett, for an institute of global studies, and $100 million from a couple for an institute of biotechnology in medicine. The Evanston, Illinois-based school, which ranked ninth on the survey, raised $537 million. The Pritzker family pledged $100 million for the law school in October, some of which will be captured in the next survey.