80-90% of them.
please don't talk about ost like it means something. the amount of athletes actually getting tested are tiny and if you're one of the unlucky few you can just decide not to test and get a warning. I think you can have 3 of those during a year without problem.
Not to mention if they actually demand you state where you're going to be for a test, there's a bigger chance they won't come than that they will.
Only suckers get caught.
eyeopening interview with Victor Conte (of balco fame)