By using 12 month index, I believe you are penalizing the vast majority of honest golfers to catch a few cheats. A person with an index of 18 on 9/1 and a 23 on 8/15 is not the same as a person with a 23 on 9/1 and an 18 on 8/15.I am assuming there is a gradual change in index over that time period. They should not be playing in the same flight !! The committee has ways of dealing with sandbaggers that does not have to affect the majority of honest golfers.