Another example of the complete misuse of statistics. Averages are meaningless because you can't meaningfully add one user's speed to their neighbour's, and averaging implies adding all the values together.
Averaging would be appropriate if you were talking about bonded IP, or PPP multilink, or multihomedness and equal cost multipath routing, where total throughout means something.
A complete different measure is needed. I'll leave that to someone who knows the first thing about statistics, which I'm ashamed to say has always been a complete big gap in my modest mathematical knowledge. (Despite what it says in the title of my degree.)