Not only did Rick Santorum give a low (compared to the others) 1.8% in 2010, but the article I linked also says he just gave 2-2.7% in the three previous years. But what's more disturbing is the horrible performance of the charity he founded. It collected at least $2.3 million in donations but gave out only 45% to beneficiaries. That is so bad it sounds near criminal (not that it's against the law, but probably should be), IMO.
2011 returns aren't due yet, but I bet if/when they are revealed we'll see a magical increase in both Santorum's and Gingrich's charitable giving. But that's how it seems to work with many politcians. As with Obama, giving goes up when it's visible to the public.
Romney is interesting in that he had zero wages. That means that even though he made millions, he contributed zero to Social Security and Medicare, not that he did anything illegal. At least part of that will change with Obamacare when investment income will get at least partially taxed for Medicare. I wonder if Romney's 2011 taxes will show he paid a higher total percentage in taxes than in 2010?