Agree that the majority are on some form of Juice. If we believe Benjo Maso, author of "Sweat of the Gods" and a man who probably knows more about pro cycling than all the rest of us put together, he says about 90% of the pro peloton are doing it.
However, I think there is a technology distinction so that the best guy may not necessarily win. Look at the way Gewiss dominated when they were ahead in the doping stakes. I think there are a few teams like that now. There was even a rider recently that was personally sponsored by BristolMyersSquibb!!!