I'm sure there are stats out there...I remember reading a TSB report a while ago (we have a lot of floatplane accidents up here in Canada).

As long as you're wearing a shoulder harness, the main risk is drowning after the ditching. To have a good chance of surviving, you need to be already wearing a lifevest, know how to open the door underwater by memory, and then be able to get out. You can do an underwater egress course, which helps increase the odds.