AIM Warning Levels

Does anybody know how the pesky warning levels work on AIM?
How is it sometimes you can get warned and only be bumped up to 5% and others up to 20% (even when the user does it non-anonymously)? How does it sometimes go down quickly, and others take forever to go down?

the warning level rise, from what I can tell, is based on how many messages you’ve sent the user warning you in the last x number of minutes.