Updated

Charitable giving in the United States increased in 2016 — but only slightly, according to the latest comprehensive report on Americans' giving patterns.

The Giving USA report, being released Tuesday, said giving from individuals, estates, foundations and corporations reached an estimated $390 billion in 2016. That was up 2.7 percent in current dollars (1.4 percent adjusted for inflation) from the estimate of $379.89 billion for 2015.

Out of the nine charitable sectors identified in the report, the biggest increase in 2016, percentage-wise, was for environmental and animal-welfare organizations. Giving to this sector, when adjusted for inflation, rose 5.8 percent to just over $11 billion.

As usual, the largest share of donations — almost $123 billion — went to religious organizations, although the increase for this sector was modest at 1.8 percent.

"This report tells us that Americans remained generous in 2016, despite it being a year punctuated by economic and political uncertainty," said Aggie Sweeney, the chair of Giving USA Foundation. "We saw growth in every major sector, indicating the resilience of philanthropy and diverse motivations of donors."

Still, Americans' level of generosity is no higher than it was decades ago. For 2016, giving by individuals represented 2 percent of total disposable income — down from 2.4 percent in 2000 and the same as the rate in 1976. Similarly, total charitable donations have hovered around 2 percent of the gross domestic product for many years; for 2016, that figure was 2.1 percent.

Corporate giving, as a percentage of pre-tax corporate profits, was 0.8 percent in 2016, less than half of the 2 percent figure in 1986.

There's considerable uncertainty in the charitable sector as to how philanthropy might be affected by a planned overhaul of the federal tax code, as well as by possible spending cuts in the budget proposed by President Donald Trump.

"Most in the sector agree that reducing income tax rates and increasing the standard deduction would reduce charitable giving," said Una Osili, director of research at the Indiana University Lilly Family School of Philanthropy.

"The sector largely thinks that philanthropy alone cannot fill the gaps created by proposed spending cuts, but beyond that, consensus is harder to assess," she said in an email. "The cuts would affect different types of charities differently because some charities rely more heavily on government funding."

The Lilly Family School of Philanthropy researches and writes the annual Giving USA reports, which are published by Giving USA Foundation.