[Adam Freeman]

Originally Posted by Andrew Schreiber

I recall he explained it because it meant that things that happened more than a student cycle ago didn't count for much.

Edit: That's why I've stolen that number for a lot of things I do too.

Yep, says that exact thing right in the notes tab of the spreadsheet:

"An annual derating factor was applied to all past data. This causes the data from past years to have a diminishing effect on the current team standings. A weighing factor of 66.66% was used. This means that the current season carries 1/3 of the weight of a team's entire calculated history over long periods. This factor was determined somewhat subjectively, and is largely based on the fact that a team's student population will turn over completely every 4 years. Thus we do not want events from over 4 years ago having a significant impact on the current cumulative rankings."