Successful Ditching - not so rare...
As far as I recall, between 80 and 90% of occupants of aircraft which ditch, survive the ditching (88% springs to mind). However, a good proportion of them (I definitely have forgotten that statistic) go on to die of hypothermia, drowning, etc.
I forget the source, but this is all aircraft, worldwide. I take it as being good reason to concentrate on decent safety kit, and knowing what to do. (Also, I don't fly single-engined over water).
If someone has the survey to hand (probably FAA, I think), I'd appreciate a link.