What I am saying is there are a lot more atheists and agnostics in jail, because they are still counted as Catholics and Protestants. And furthermore, yes, I would be willing to bet that anyone who has taken the time to think about how they should be categorised probably is less inclined to be in jail. In other words, the Jews who want to be Jews are not likely to be there. The atheists who want to be atheists are probably pretty moral folk. The Catholics who want to be Catholic are pretty moral folk. The people in jail tend to reflect the people whose religion is theirs only by heritage, and there are very few people who get atheism from their parents. How many seriously devout Catholics in Australia are mass murderers? Not many. How many massive bank robbers are regular attendees of Baptist churches? Not many. But I'll bet that both, when asked, gave a label. They probably didn't say they were atheists, even if they actually are atheist/agnostic in point of fact.
Statistics are like bikinis. They show a lot, and they hide essential parts.