I think there are a few sports where doping does not give any big advantage - especially accuracy and agility sports - shooting, boxing, archery, tennis, gymnastics,badminton, hockey, football ..... So they tend to be clean..... But there are sports where doping gives huge advantages - strength and speed sports - weightlifting, - cycling, atheletics, swimming and to some extent wrestling ---- here doping is rampant and technology to catch dopers is always 3-5 years behind doping........... Also some countries are covering up doping or because of huge money there are well set up commercial organisations........