I think that weed is more popular with musicians than actors. Of course, there are excptions like Nicholson. He definitely used to smoke, but who knows if he still does. At one time, almost everyone in Hollywood had at least tried it.

I can't imagine many of today's working actors being stoned on weed very often because it would probably get in the way of their job. More likely than not, they're prescribed other stuff like anti-depressants, stimulants, etc.