99% of the time dog aggression issues are really just handler issues, start when they are pups and show them it will not be tolerated, and never leave them loose and unattended when they aren't being used.
i think your percentile is a bit on the high side. some dogs are just naturaly aggressive. before dispatching, iv tried electro theropy and switch to butt theropy. i would venture to say aggression is around 50% handler.