25% initially, falling back to 6-8%, the difference being helped by a variety of methods including drugs and exercises.
Fair enough. I'm pretty sure your claim that the prostate prevents incontinence is wrong though. Micturition is controlled by the muscles of the bladder wall and the internal and external sphincters. Surgery can cause damage to these or their nerve supply, resulting in incontinence.
There's movement of the prostate while peeimg, according to recent research, but I suspect this is to do with preventing urine entering the seminal ducts.