There's a lot of variables involved with a defensive incident. Even the defenders own perception of events is altered by the nature of it.
Further , I'd wager the majority of Joe Public CCW incidents are resolved without shots fired- bad guys out to score money or a car don't want the loot bad enough to get shot over it. The moment Mr Thug sees a gun or the possibility thereof he's outta there--its something I've seen firsthand .
Now ,crossing over into the land of total speculation id posit the cases of citizens actually shooting at bad guys is more frequent when it's a home or business robbery; in those cases the bad guys have advance time to determine what the payoff is and are committed to the attack .