So to add a bit of info. This change was made to better handle check in with the larger aircraft as it would be reasonable for an airline to open a certain amount of desks depending on the departing passenger count. When doing tests with the A380, 3 desks where simply way to few and caused massive delay. So we changed it and 1 desk per 75 passenger is a rough value but it is set so that most medium flights will at least open two desks. Each flight passenger count, like Olof said, is randomized in between (for now) 35% to 100% of the max capacity. We have set the minimum value fairly low for now, as we have some challenges with long path finding calculations that appears when the total passenger count get in the several thousands.
Here is the full list and the max pax per aircraft. 
"1900D" 19
"A319" 124
"A320" 150
"A321" 185
"A330200" 253
"A330300" 290
"A340300" 290
"A380" 555
"ATR72" 70
"ATR42" 48
"B737600" 123
"B737800" 170
"B757200" 200
"B777200" 305
"B777300" 365
"B7878" 242
"B7879" 290
"B78710" 330
"BARON58" 5
"BAE146" 123
"CESSNA208" 9
"CRJ200" 50
"CRJ700" 78
"DHC6" 20
"E170" 66
"E190" 98
"Q400" 82