My very unofficial experience would be one in 6. You don’t know about the problems until you share your problems. Not everyone is long term problems but there is something that is not the easy 3 days most doctors will tell you. Literally Russian roulette
After almost 2 years, I’m finally not in pain most days but my boys will always be tender and easily irritated. My epididymides are permanently enlarged and firm. This makes me afraid that an impact could cause a major blow-out of one of them. Remember that you are asking your system to deal with back pressure it was never intended to endure.