Graft is money stolen by the local officials. Graft is calculated in the following manner:
1. Graft is randomly 0 to 30% of your surplus.
2. If you are paying your a officials less than 4 Kducats per thousand of population you can have 2% to 20% more graft. The less you pay the more graft.
3. If you bailiff skills are bad you have the chance of having more graft also.
Let's take an example. If you had a surplus of a 100 Kd and then system generates a number between 0 and 300. Let's say it generated 15. Your base graft would then be 15. Now we see you are paying the officials 3.5 Kd per thousand that increase graft by 2% so now graft is 15.3 Kd. Let's now assume that your bailiff is a real idiot and the chance of him having more graft is 70%. He fails his roll and now graft jumps by another 80% so now graft is 27.5. So lets look at a worse case and a best case. Best case is 0 graft. Worst case for a surplus of 100 Kd would be 64.8. So you could see big swings from season to season.