Probably a good few times.
The two substantial ones that I remember are once when I was probably about six, when I was at a gas station in Illinois and one of those old-timey light fixtures fell down and hit me. I don't remember much from the accident but shortly afterwords I do remember a paramedic examining me.
The other time was slightly later, when I was about eight, when I decided to drive a mini-motor cycle around my apartment complex. Needless to say, I was driving at least ~30mph and didn't know how to use the breaks. I nearly collided with an SUV backing out of a parking space, and then skidded across the pavement, losing ~90% of the skin on my left arm, busting up my left knee and even my left shoulder.
Good fun.