Cheick Kongo publicly stated 50%.
Krzysztof Soszynski publicly stated 50%
Mac Danzig publicly stated 90%
Denis Hallman publicly stated 50%
Victor Conte publicly stated 50%
I would say it is safe to say a large percentage of mma fighters have abused PEDs.
Big name fighters who have been busted for PEDs:
Did I mention Josh Barnett?
Oh yeah, Josh Barnett
Jeff Monson - Not caught but admitting to steroids
Kevin Randleman - Fake piss sample
And that is just a list of 'name' fighters who have been busted.... Gotta be some truth to the claims.
Oh and King Kong was really in that pic?