Atheists and prison (not the same as the other atheist prison questions)?

i already know that a smaller comparative amount of atheists are in prison then christians, catholics, etc. the last number i saw was 0.2 percent prison inmates being atheist, while 5-9% of the total USA population is atheist. i want to know how many people are atheist upon entering the prison, however- so, how many are atheist when they do the crime. i myself am atheist, and me and my freind often debate religion. he says the conversion rate in prison throws of the 0.2 statistic. I want accurate facts to argue with. thanks in advance.