what percentage of humanity thinks themselves as heroes?

I'd guess that around 40% of humanity believes they're heroes -- a person capable of acting heroically in times of danger. But psychological studies say that when the rubber really meets the road, or the sh** hits the fan, the actual number is closer to 20%, or one in five, who will actually put themselves in any kind of danger to save someone else from injury or death. Remember, a "heroic act" is not an unthinking plunge into an icy lake to save someone, rather, it's an act "performed with recognition of possible risks and costs, be they to one’s physical health or personal reputation, in which the actor is willing to accept anticipated sacrifice," according to an article in Greater Good Magazine.