Japan has always had a long tradition of distance and marathon running, and they used to be a real power on the global stage back in the 80s and 90s. Looking through lists of banned athletes, there seem to be very few Japanese distance runners (not that this is any indication), and so the conclusion seems to be that Japan is the 'cleanest' distance running nation and neither state nor individual level culture of doping or cheating has ever taken hold.
What do others think?