The problem is, is that the number of these events is neither just above zero or exceedingly rare. A recent Bureau of Justice Statistics report stated that between 2003 and 2007 about 3.7 million burglaries were reported. And in 7% of those burglaries, a household member was the victim of some sort of violent victimization.
Using my trusty calculator, that comes to 259,000 violent crimes committed during burglaries every year. That doesn't seem exceedingly rare to me.