At each tournament:
1st place gets 25 points
2nd place gets 18 points
3rd place gets 15 points
4th place gets 12 points
5th place gets 10 points
6th place gets 8 points
7th place gets 6 points
8th place gets 4 points
9th place gets 2 points
10th place gets 1 point
11th and lower get 0 points

Total points are a sum of:
100% of points earned at most recent tournament
75% of points earned at 2nd most recent tournament
50% of points earned at 3rd most recent tournament
25% of points earned at 4th most recent tournament

Points expire at a rate of 25% per tournament
Points at the most recent tournament are weighted more heavily