WASHINGTON - November 15, 2010 - Almost 15% of U.S. households experienced a food shortage at some point in 2009, a government report has found.

U.S. authorities say that figure is the highest they have seen since they began collecting data in the 1990s, and a slight increase over 2008 levels.

Single mothers are among the hardest hit: About 3.5 million said they were at times unable to put sufficient food on the table.

Hispanics and African Americans also suffer disproportionately.

The food security report is the result of an annual survey conducted by the U.S. Department of Agriculture (USDA).

Households deemed "food insecure" experienced a period of inadequate food supply as a result of their economic situation, but did not necessarily remain without sufficient food for the entire year.

Although the number of food insecure households has risen sharply since the Depression, the USDA says the growth rate has slowed, particularly toward the end of 2009.