I'm not sure such statistics are made publicly available, but the good news is that clearly AdCom still is interested in your candidacy given that they are not inclined to decline you at this time.
There can be a variety of reasons why someone may remain on the waitlist. Some factors may simply be beyond your control (e.g., how many people of a certain type of profile accept, how your profile would bring diversity and color to the class given who accepts, etc.).
Truth be told, there is no easy way to say how long you will or will not be on the waitlist. All that can be said is that, as I mentioned before, Wharton is still interested in your candidacy.
If the issue is that you have to decide whether to accept another school's offer or not, I would say you have to weigh the benefit of the certainty of an offer against the risk of not being accepted if you wait out Wharton's decision in your case. I wish I could tell you you have X% chance of being accepted or denied off the waitlist, but it just isn't so clear cut; it depends on each individual and how they would fit into the bigger class picture. An aggregate % figure would potentially be misleading, even if available.