For furry pedophilia, I couldn't find any statistics. I acknowledge they exist, but in very small numbers.
For furry porn addicts, 5% reported joining the fandom for the sake of said content.
Rule 34 is a rule of the internet, not a category of people that can be counted. If you read rule 34 already, you should know that if anything exists, it has an NSFW artwork of it on the internet (Which also explains why porn of cartoon furries exists).
As for the entire fandom, 0% of the furry fandom is a part of the furry fandom, though I have my doubts...