One of the basic tenets of statistics that every student learns in about the second week of intro stats is that in a skewed distribution, the mean is closer to the tail in a skewed distribution.
So in a right skewed distribution (the tail points right on the number line), the mean is higher than the median.
It’s a rule that makes sense, and I have to admit, I never questioned it.
But a great article in the Journal of Statistical Education shows that it really only holds in idealized, unimodal, continuous distributions: http://jse.amstat.org/v13n2/vonhippel.html.