I am not sure. I think they may fire them more in small rural departments, but it is for a different reason. In rural areas, it is much more likely to be fired at a wild animal (snake mostly) or to put an animal down (less animal control working and more car/wild animal accidents). In a big city, it is more likely to be crime related.
I think it looks interesting and I want to see more detail on it. The question of just firing a weapon on duty includes lots more than most people would think. When I first saw the number, I thought wow, that is way high. Then I saw the question and said, nope, way too low. I know a lot of officers who would answer no but probably should have answered yes. The problem is the shot fired was borderline on being justified and hit no one, so it never got reported.