One of my closest friends, we grew up together, known him my whole life. He played ball for the Rockies for 5 years...hurt his knee and that was that.
Point being, I asked him once, "How many of the guys use anything, half?" Half was my guess.
His answer "All of them...maybe a few don't but I don't know who they are."
He said it was no secret, everyone was pretty open about it, it's in the locker room and talked about daily. He said about the time he stopped playing though, that was about the time the witch hunt really got going, he said then it did start becoming a little more of a taboo topic but "in house" it was still talked about as much as ever.