top 100 question

[ca****]

I was just browsing the site and have come across the top 100 thing a couple of times.

Just out of interest - how does that work?  It puzzles me that some of the top 100 active and popular people haven't been on the site for months?

Or was it a sample taken a good while back??
It is my inquisitive nature that has me asking

 

[ey****]

I've raised this before also - it clearly seems wrong