I've been bucked MANY times but I rarely fall off. I think I've only been bucked off twice... Both by my old blind appy, Tater. The first time was when I didn't know he bucked and I was doing a 4H drill. The other time I semi-expected the buck but had no idea he was going to rear before the buck. Needless to say, I hit my head on his and slid off after his little 'explosion'. He bucked me multiple times between those two events and multiple times after.. Which, unfortunately, led to me selling him.
I've also been bucked by my pony and by my aunt's horse that had a bucking issue.. I'm 99% sure I rode the buck out of him. Unfortunately, when I was improving her horse, she was letting mine spook out on trail -_- So, yea. I've been bucked off twice.