Too many, but since I stopped racing many years ago I have had far less, although I have had a few almost serious MTB crashes in recent years. Worst racing crash was coming down in a school boy circuit race, out cold, woke up in the ambulance, then passed out again, was out for several hours, only time I've ever spent a night in hospital. Most interesting crash was coming down in a Devil during a Reading track league race, about 7 of us left, I still claim I wasn't the last over the line, but I was the only one on my ar$e.
I've also had several collisions with cars, one was in a Crit on non closed roads, it was a head on with a learner driver, and my fault, still have a few scars from that one, although after having lots of X-rays, and bits of glass removed, I wasn't too badly hurt, and they let me leave the hospital that day. Three collisions with cars that were the fault of the drivers, but looking back, the young indestructible eejit I was at the time, I didn't exactly do the right thing to avoid those accidents.
I did have very close shave with a car last week, it really was a bit of dumbness by me, and only thanks to the driver reacting quickly enough did I get away with my arm just brushing the side of the car, and nothing more serious, not even a bruise, not sure why I was such a numpty on that occasion, it's been a long time since I could blame it on young stupidity.