The CBA must have these figures, but in my 15 years of arm's length experience with them, I've found they rarely release any numbers of any kind. If I'm wrong, it'll be Michael Hiatt who proves me so. You might google his recent blog posts, if any, that attempt to explain the Christian fic market.
That said, I've always heard that in the C-fic market, if you write anything that offends a reader, they will march the book right back into the store and demand a refund. I once asked my then-agent about how frequently this happens. I wanted statistics. She gave me a blank stare and replied, "Everyone knows this happens." I asked, "How often?" I got the same blank stare. So I told her point-blank, "If nobody can produce any numbers as to its frequency, in my eyes it's unproven. Therefore I'll act as though it's an urban legend, and ignore it."
C-fic is full of instances like that, things "everybody knows" that nobody can prove. I wish you well in the journey.