As was stated previously in this thread, Dominion contains a lot of good art. I did a little averaging this morning and this is what I found.
Based on our scale of 1 to 7 (1 being worst), the average for group Z was 2.4. The average for group W was 3.3, nearly 1 point difference.
Average in group T was 3.7, group Q 3.9, and group N 4.1. So the difference between Z and W is greater than the difference between W and N. As we move into the large group of pretty good art, the slight change in a single vote could move a card several groups up or down. There is going to be a lot of head scratching in the next 200 cards or so. Teenage preference is going to weigh heavily into where any card ranks.
By the way, the average of all cards was 4.2 which is very close to the center of the 1 to 7 scale.