ratingrule.txt, 05 may 2005
spot writes:

the rating is divided by 4,
and then when votes come in they keep adding
in to the current rating.
he rating is a recursive filter
of the votes.
this is it:

when user votes:
rating = rating + 1;  (sometimes -1)
if (rating > max) max = rating;

once per day:
rating = rating/4;
round down

the value we have for stats is "max".