Years ago I saw somewhere that an estimated two million bikes are stolen each year on a population of (then) fifteen million people. So that averages out to once every seven years if everyone rode bikes, but if we remove the really young and old that's probably closer to once every six years.

This does not represent my experience at all, I've had bikes stolen once every three years on average. It won't surprise you that students learn to buy very cheap second-hand bikes with very big bulky locks really quickly here.

On the plus side, I've never been worried about junkies mugging me. They steal/sell bikes for drug money instead, and I honestly wonder if that is a uniquely Dutch thing.