I'm not sure if this is what you are looking for but here is a link for you.

Utah big game report

Its a lot of data but pay close attention to the Classification summary on each unit (1 unit per page). It tells you success rates, the number of mature bulls there are per 100 cows and lots of other info.

The elk info starts on page 67.

Also check out this link in the proclamation. It tells you the average age of harvested bulls on each unit.

Utah Big Game Proclamation

You want to look on page 69.