Average and median aren't the same. It's likely more than 50% are below average. If zero is the limit as far as how far down the scale you can go but there is no limit to how much you can excell, you'll likely see a distribution skewed to the left. This means that the median will fall to the left of the average.

Tldr; I completely miss the point and instead talk about how average is kind of a shit metric sometimes.