[ghaff]

If by serious injury, you include things like ACLs, certainly.

If you mean broken legs, spinal injuries, etc. that's going to vary a huge amount by what kind of skiing you do. If you're a racer in Downhill events, that's one thing. (How many times did Lindsey Vonn seriously injure herself?) Add in high speed tree skiing much less more extreme off-piste skiing of various kinds.

But a recreational skier doing basic blue and black diamond runs with a fair bit of caution? It's pretty safe. Sure, you can wipe out on ice or someone can blindside you. Or you can hit your head--although many wear helmets these days. But, overall, I'm guessing the driving to the hill is more dangerous. (Often fairly long drives in winter conditions.)