Are you sure it isn't the mode? All mathematical joking aside. The median would likely be much more representative of most people. The average is easily skewed by outliers.

Even if most intelligence measures / tests weren't horribly flawed. Most people cluster closer to the bottom than the upper bound. But every gifted outlier pulls the average higher and higher above most people. Hence the average being above most people.

just adding this in for a point of reference. But it is a paraphrasing/reference to a George Carlin skit.

"imagine how stupid the average person is then realize half of all people are stupider than that."