Income is a fixed percent of the materials in each sector you own, which does not degrade over time (at least in this version of the game; a version 2 will likely operate differently).
So, the average money per sector is simply the amount of money you made in the last turn divided by the number of sectors you own.
So, everyone may want to keep in mind that revealing your average income per sector also reveals to your enemies exactly how much money you're pulling in per day.
Now let me know if you guys want me to delete this thread.
