The number you have for your hub is called as "Hub Score". It depends on various factors like
1. Uniqueness of your hub
2. Size of the hub (more than 800 words will have good score always)
3. No. of views (traffic) it gets.
4. Comments and discussions it triggered and so on....
If your hub has more score value, then it would be pushed to the top of the search engines and will get more traffic to you.