Ahtletes didn't begin doping in the 90's, 80's or even 70's. Unfortunately, it has been a huge part of "Big sports" as Jimmy put it for a long time. I really doubt the recent scandals will clean anything up. Maybe temporarily, but when the ADA's shift theyre focus to another sport, it will be back.
A little timeline on doping in sports
http://sportsanddrugs.procon.org/vie...ourceID=002366