This is your hubber number. It is based on how you interact with the site. It goes off of how many hubs you have published and how well the are doing as well as how much you comment on other people's hubs as well as how many fans you have compared to how many people are your fans... I think. It is also based off how much you post in the forums too.
The higher your number the better and as you continue to post good hubs the number will rise. But if it drops below 75 apparently your outgoing links from your hubs stop working. I don't know about that though. I've managed to keep a high number.