How does the rating system work for interests?

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I have noticed that the interest rankings are either not updating quickly (and I mean within a week) or they have a weird system for determining these rankings. For example, i must have made at least 20 very long posts in the baseball interest, yet my ranking in that interest moved from 105 to....105. I don't get it. I am a very competitive person, so naturally I wanted to be #1 in each of the sports categories. So I was surprised when my ranking didn't move. (I made these responses about a week ago). Any ideas/ help?