Private foundations earned more, gave more and received more contributions from their donors in 2017 than they did the year before, according to Foundation Source, a support organization for private foundations.

The foundations also gave away more than the required 5 percent of assets during the year, according to organization’s “2018 Annual Report on Private Foundations,” released Wednesday.

The report studied 927 foundations with less than $50 million in assets. Foundations of this size represent 98 percent of approximately 83,000 private foundations in the United States.

The assets for private foundations grew 13.2 percent in 2017, whereas they had grown only 6.6 percent in 2016. Part of this growth was due to favorable stock market returns, but it also reflects an 8.3 percent increase in contributions by the creators of the foundations, the report said.

“The high rate of contributions is a good indication of donor commitment to and enthusiasm for their private foundations,” said Page Snow, Foundation Source’s chief philanthropic officer. “Rather than relying on investment returns, donors are providing infusions of fresh capital to fund their charitable interests.”

The 927 foundations together gave $285 million in charitable contributions compared, up from $266 million in 2016, distributing on average 8.2 percent of assets, substantially above the 5 percent distribution required by law. The smaller the foundation, the higher the percentage of assets distributed: Foundations with less than $1 million in assets gave more than 13 percent.

“At the conclusion of 2017, the foundations in this report were in a position of great strength and vitality,” the report says. “Impressive portfolio performance and infusions of donor capital fueled asset gains, potentially setting the stage for robust grant making in 2018.”