I could be way off since, as far as I know, there are no stats on this kind of thing, but if I had to guess, I would expect the semi-pros in the middle are a relatively small number. I'm sure it depends on where you live, what neighborhood you're in and all that too. It doesnt really take much to be "pro" enough to defeat any bike lock. A long set of bolt cutters, maybe a battery powered angle grinder, and a pickup truck and you're set.

The only time I had a bike stolen was when I lived in campus housing and had to leave the bike outside chained to the building. A crew came through on thanksgiving day, apparently with giant bolt cutters, and loaded up a truck full of bikes. I doubt any lock would have stopped them. They knew most students would be gone and they brought the tools they needed.