Sorry, I didn't fully comply with your post parameters.
As for American, I'd believe Ryan Hall was clean with high confidence. He definitely is not the fastest "clean" athlete by any means, but I don't think systematic doping is a 100% conviction type thing at this point.
Even with the latest report, there are some very significant numbers, but only 800/5000 have "suspicious" blood levels. To what extend that means, its still 17% or so at the highest level.
Even at 1/3 of medals, Russia offset the results somewhat for their high number of suspicious athletes. Makes sense, they've had some notable high level bust often. There's still quite a few clean athletes, not everyone dopes.
I understand your post, but I also think its worth noting that theres clean athletes from all over the world running fast.
A better questions to ask is the contrarian questions: How many people are capable of doping? Not everyone is "capable" of doing, or committing an act of bad ethical standards. For instance, the moral high ground is still strongly prevalent with our sport, which is why it still is a major issue to both athletes and fans. I don't think all athletes are "capable", yet are very fast and accomplished.