I think you can get an idea by the latest prices for the flight, and by how much the flight has gone up since it was posted. We're leaving Dec 12, and our flight started out at $79 and now is $139. I will guess that flight is pretty full. However, they still have a couple flights the same day at $79.
I also noticed that all the return flights for our trip home are very expensive. Again, we booked the first day they were released and paid $79; now is $169. In fact, the cheapest return is $126; the highest $206. Lots of full flights!