Only two so far.

1. Not long after passing my DAS I failed to get round a corner, saw a car coming, panic-braked and shot off the road resulting in a broken back. Burst T-12 vertebra from going over the bars, flying down a bank and landing on my arse. Was only doing about 50mph, but had been taught NOT to counter-steer by my instructor, so couldn't corner properly >

2. Later that year I got knocked off when filtering round a gridlocked roundabout which suddenly cleared as I was trying to exit it, got bounced off the side of a car that suddenly appeared next to me.