That's one of a number of reasons I carry a J-frame EDC. It's much harder to take away if it's in my hand--the barrel is short, and the leverage is mine. But I don't know where you'd find figures on how often it happens.
I am sure that number would be directly tied to how often the CCW person trains with their weapon. For some of us that would be almost an imposibility. For others they are simply lucky that it hasn't happend yet.
Romans 1:16 I am not ashamed of the gospel, because it is the power of God for the salvation of everyone who believes: first for the Jew, then for the Gentile.
Is it all about training? We have no idea how many people are armed each day? How many times does a civilian use his firearm to stop a crime without firing? We just do not know?
Police however are trained and retrained. Each time an officer is involved with the use of a firearm it is recorded. So we know that 511 officers well trained were killed with their own weapons from 2000-2010.
I always hear it will happen, must happen, lucky it hadn't happened yet. Yet no one, and I mean absolutely NO ONE has ever been able to provide the answer for me, to the very same question you've asked.
I have heard stories (legit, from newspapers) of robberies resulting in a stored gun being taken, FROM IT'S STORAGE PLACE, i.e. closet, behind the door, etc. etc., and used against their owners, but NEVER have heard of one being snatched from the hands of the owner or from a holster of someone legally open carrying.
That's more a gun storage issue rather than an oc vs cc issue.
That pretty much the response I expected. Just wanted to make sure. It's interesting that there is almost so data or really anything else on this. I can't really recall ever hearing about something like this happening. Like trip said, you'll hear about stored guns being used, but never concealed guns.