I won't be able to give you a figure on the exact number of stolen vehicles at dealerships off the top of my head, but I could look into that, for sure.
The cases I'm referencing are well known and documented in the media. Sales folks run over as they get strong-armed in a robbery. There's a very famous case in British Columbia where a police officer was shot responding to a Chrysler dealership that was being robbed of vehicles at gunpoint. Dealerships across the country can all tell you stories about people coming in for test drives, and then snatching the keys and bolting that way.
It's a pervasive problem.