Interesting that the age group 42-49 is considered 'young' by that piece...
My problem with that report is that many churches require a donation for 'church-run charities', was this differentiated from truly voluntary donations rather than 'someone's handed me the donation tin in the middle of a church, I'm going to look bad if I don't put money in'. Also, it's a common problem with any scientist performing studies on people that physics doesn't lie, people do. Some religions require a percentage of the persons' wages, they would consider that as a 'charitable' donation, because it sits more easily with their phsyche than thinking the money is taken from them.
Frankly, the whole idea you can define charitability from Social, Religious or Political leanings is a pretty iffy bit of spin-doctoring, apparently, if you are a secular liberal, you are a tight fisted bastard according to that report, I have to question the neutrality of the person creating it. I suspect there is a certain amount of bitterness amongst secular people in the US, when you have Fox News claiming that appealing to atheists is 'offensive' in Obamas inauguration speech, I don't expect they really feel all that welcome in the US. But the US is not the world, it's a very strange society in a lot of ways, constantly at war with itself over what 'Freedom' is, and who it applies to in what way. It's very difficult to set a religious 'standard' of behaviour from the US because many people say they are religious purely to avoid being persecuted for not being so.
Edit: Look at it this way, we've got the Pope here in the UK at the moment attempting to re-write history and Hitlers motives behind WW2, purely for the sake of demonizing atheists. I don't think it will work, because he picked the wrong country to say it in, the UK is pretty aware of the history behind WW2, but there are countries where that kind of claim would have taken a hold because people wanted to believe it. I would include the US on that list.