New York —- Americans gave to charities last year at about the same rate they did the previous year, holding steady on their donations in the face of a housing-market meltdown and a crisis in credit, a study being released today shows.

This year, soaring gasoline and food prices have been added to the economic worries and could lead to a drop in giving, nonprofit groups and fund-raisers say.

Donations by Americans to charities remained at 2.2 percent of gross domestic product in 2007, according to the yearly study from the philanthropy-tracking Giving USA Foundation.

The study shows that charitable giving in 2007, measured as a percentage of GDP, matched giving levels in 2006 and from 2002 to 2004. Giving was boosted in 2005 by aid for victims of Hurricanes Katrina, Rita and Wilma and the Asian tsunami.

After a strong start last year, stock market trouble and the housing and credit downturns put a drag on charitable contributions for the balance of the year.

"The year started out to be a good year, then the economy started to get really shaky in the fall, and that's when a majority of people start to do their year-end giving," said Edith Falk, chief executive of nonprofit consultant Campbell & Co.

The 2007 contribution total —- including donations from individuals and corporations —- was estimated to be $306.39 billion and had risen by an inflation-adjusted rise of 1 percent.

Aggregate personal income rose 3.3 percent last year, but giving as a percentage of that stayed at 2 percent, the same as in 2006.

"I think people are naturally worried," said Del Martin, chairwoman of Giving USA. She said smaller nonprofits are most vulnerable, but that if gas prices continue their march upward, then individual donors will cut back and the entire nonprofit sector will suffer.

Individual giving, which accounts for the biggest chunk of total donations, dropped by 0.1 percent on an inflation-adjusted basis in 2007 to an estimated $229.03 billion. Corporate giving also fell as companies pulled back, and the total dropped to $15.69 billion, or 0.9 percent lower when adjusted for inflation.

Jeffrey Bentley, executive director of the Kansas City Ballet, said he fears the current economic slowdown will affect all nonprofit fund-raising this year.

"I think this perceived economic malaise is different, because the issues are so much in everybody's face," he said. "You can't drive down a street without seeing what gas prices are today, you can't pick up a newspaper without seeing housing prices, you can't buy a house without realizing there's a credit crunch here.

"I can't imagine that we are not going to be really hard-pressed to maintain any kind of forward movement," he said about this year. "It scares me. I wish it weren't true."