How about a much more useful question, how many times are handguns used to scare off a would be attacker?
(Your response) How about a much more useful question, how many times are handguns used to scare off a would be attacker?
Your question does, of course, reflect the most important issue of deterrence. Their stated assumption - killing is the objective.
Another point to add is what armed women should focus on when facing an attacker. The objective is to stop the attack and survive unharmed, as opposed to killing. It's well to keep in mind "I shot to stop, not to kill."