Perhaps you misunderstood, I was suggesting a "Current Average In" box rather than a "Average In" box.
If you didn't misunderstand, maybe I have an older version.
I did a little test, opened 5 connections to gnutellanet, my incoming bytes were 5k/s, I disconnected all of them, and it took 10 minutes for the average in to go from 5 to 1.5