That's like saying that flu kills more people on average than the plague, since more rubber bullets would have been fired than proper bullets.
Rubber (or nylon, which they're made out of now) bullets are actually very dangerous things. It's not like they just wind you, if one hit you in the ribs you could come out of it with a crushed lung and broken ribs. If one hits you in the face, it'd be like getting hit in the face with a cricket ball fired from a cannon :-\
The idea is to shoot them at the floor so the skitter at knee level and take people down like that, without doing any major damage, since a lot of kinetic energy is sapped when the bullet bounces off the floor. People seem to think that you can whang rubber bullets into crowds and not kill anyone, but that's far from the truth, considering a rubber bullet's basically a solid plastic 40mm grenade fired from an M79.