a better question would be how many in a typical franchise gym in a middle class city in America. i would estimate a majority for sure have used or are using. the sad thing is they look like shit anyway
so my point is pros are athletically gifted, steroids are simply a small tool in their arsenal and to answer your question i can almost guarantee you a huge majority use HGH. it is very difficult to test for. also MANY smoke pot (NFL players are only tested once a year and are given ample notice)