At this moment I have two above 90. But that changes consistently. I have three others right now that are 89 each and sometimes they go over 90 also. So at most I had five Hubs at one time over 90.
It's interesting to see how they fluctuate. There are many reasons for this, but my guess is that the Hub Score has a lot to do with the following: The number of thumbs up, length of time people stay (actually reading) the Hub, number of external incoming links, spelling errors, and proper use of capsules.