i think this is interesting:
Percentage of Income Donated to Charity in 2011:
Barack Obama: 14.2% of Personal Income Donated to Charity in 2011
Mitt Romney: 13.8% of Personal Income Donated to Charity in 2011
Newt Gingrich: 2.6% of Personal Income Donated to Charity in 2011
Rick Santorum: 1.8% of Personal Income Donated to Charity in 2011
(source: Washington Post).