If you assume a normal distribution, it is statistically impossible for more than 50% of people to consider themselves above the mean on a given metric. However

If you assume a normal distribution, it is statistically impossible for more than 50% of people to consider themselves above the mean on a given metric. However, if the distribution is severely negatively skewed (i.e., the "bulge" of the distribution is moved to the left and there are many outliers below the mean) then more than 50% could be above the mean because the outliers on the left end of the distribution drag the mean down significantly.