Filter auto-infra increase for small airports

[Tha_Ape]

In GW#4, TJMZ, a very small airport in Puerto Rico with only domestic demand (3 routes totalizing 18 demand, 3x6 pax) has just been selected by the random tool to have its its infrastructure increased from 1 to 2.

This is fine, in some way. The problem being that there is a good number of such small airports around the globe with a ridiculously low demand that compete for random increase with airports that actually have a demand, but which can't be served (because of low infra), either pax, cargo, or both.

Thus, it would be very nice if the system would select airports with at least an average demand to be eligible for a random increase. Or give them a higher factor / chance of being promoted.

Thank you.