[Excaliber]

I wonder if this is a more of a reflection of wealth than giving. The data is likely based on tax returns and looks at itemized deductions. Something those with wealth are more likely to do than those without. The weathier you are the more likely you are to be Republican. Giving to charities is a good way to reduce your tax bill. All in all, I'm not sure the data is all that reliable as to who is "more generous".

Let's 10% of your income is used for what ever you want to do, beyond your cost of living. If your making a good salary already, 10% may not have much impact. But when your just barely making it, 10% could be the difference between making your mortgage payment or not.