A bit obscure, but here's a brief bit about what people know about their own health -- specifically about their cholesterol. Survey says: only a third know their own cholesterol level.
Shamefully, I don't know mine. At least not lately. The survey found only two-out-of-five know high levels can cause atherosclerosis (plaque buildup in the arteries). For you non-math majors, that means three folks out of five don't know this.
I did at least know that one (he said, sitting in his office chair, letting plaque build up).