America’s poor and lower-income earners give more on a percentage basis than those in higher-income groups. They tend to keep up their giving in tough economic times, according to McClatchy Newspapers.

This is a trend I've personally seen in the many non-profits my company works with. Higher dollar donors have cut back more than donors who give between $25 and $250. An obvious reason is that people who are poorer have not seen their investments decimated. And the psychological factors related to giving are affected by fear and loss.

"The latest survey of consumer expenditure by the U.S. Bureau of Labor Statistics found that the poorest fifth of U.S. households gave an average of 4.3 percent of their incomes to charities in 2007. The figure for the wealthiest fifth was 2.1 percent, and no other quintile gave more than 3 percent.

"Among the reasons cited for the disparity are that poorer Americans tend to know more people in need, and that people with less money include disproportionate numbers of women and the elderly, groups studies have shown to be more generous givers."

A factor not mentioned, but likely relevant, is that people who are poorer tend to be more religious. And religiosity tends to make people more generous.