108,000 to 3 million lol, so basically no one knows. How many are successful? A citizen with a gun didn't stop ANY of the mass shooting over the last few years.
Around 40,000 people were killed by guns in the US last year. I bet many of those were also carrying a gun for protection...
Mass shooters don't target places where the general public might be armed, they target schools and places where guns are banned, that's completely obvious