My two cents --
7" is large, but not exactly uncommon, so I would say 7" is on the cusp of large-average and hung. Between 7" and 8" is impressively hung, and between 8" and 9" is unusually hung. 9" and over is especially hung, and anything over 10" is phenomenal.
At the other end, a lot of men have dicks in the 4.5" and 5" range, and although this seems very small to me, statistically, it's not unusual.