Of course, the answer to that question is obviously "too many." This sort of tragedy is completely avoidable, and should never, ever happen. Not even once. But it has, and it still does.
Money Geek has published a list of the 10 most stolen vehicle makes and models in Illinois, and you probably have one sitting in your driveway right now.
I was tempted to start this by saying "hey, we've all had a speeding ticket at one time or another, right?" But, after asking around a little bit, it turns out that not everyone has.