Wayne, of course. But I don't think that's changed in the past 30 years.
Angel Heredia sold and served PEDs to many Olympic winners for years. When caught, he turned state's star witness against Marion Jones, Tim Montgomery and others. Before the Olympic games in Beijing, Heredia told Germany’s Der Spiegel that, regarding the 100-meter final, “the winner will not be clean. Not even any of the contestants will be clean. There is no doubt about it, the difference between 10.0 and 9.7 seconds is the drugs.”
Another article, in the New York Times in 2008, said, "Among his clients, Mr. Heredia identified 12 athletes who had won a combined 26 Olympic medals and 21 world championships. Four of the 12 athletes, including Ms. Jones, had been named and barred from competition for illicit drug use. Eight of the 12 — notably, the sprinter
Maurice Greene — have never been previously linked to performance-enhancing drugs."
Also from the Times article:
"For years, Mr. Heredia said, he helped his clients flout the rules and easily avoided detection. Substances like human growth hormone and the blood booster erythropoietin, or EPO, are still virtually impossible to detect, and “it is still easy to use testosterone” with fast-acting creams, he said. “You combine all these things — boom! — you get amazing results,” Mr. Heredia said."
There are multiple reports that Heredia has been working with/coaching Usain Bolt for years now as well.
So while testing has gotten more sophisticated, so have the ways to dodge the tests. My guess is that few top track & field athletes are clean. It's too much a disadvantage, sort of like playing the PGA tour with 1990 balls and clubs.