I don't know the actual stats, but the danger of motorcycle riding is something that you are constantly aware of when on a bike.

You're constantly scanning for that one car that won't see you and plow into the side of you, and if you're in the hills a lapse in concentration or patch of gravel can throw you off.

What I mean by that is it's much easier to identify it as a high risk activity compared to alcohol or cigarettes since the risk is an in your face might end you today, rather than an abstract idea of this will hurt you in the long run