Is Game of Thrones really HBO’s biggest ratings hit? How are Girls and Enlightened doing? How many people watch True Blood?

Below, you’ll find HBO TV show ratings averages as of Sunday, January 20, 2013; the end of week 17 of the 2012-13 season.

Because there are fewer HBO shows and they don’t adhere to the traditional season, for comparison I’ve also included the most recent seasons of shows that aren’t currently airing.

Want more ratings lists like this? Here you go: ABC | CBS | CW | FOX | NBC

Want more info on recent/current/future HBO shows? Check our latest HBO status page to see which shows have been cancelled or renewed, how many episodes there are this season, and when shows will be returning or premiering.

This chart incorporates the final show ratings (reported by Nielsen) for the initial airings. Because the demo isn’t as important, I’ve sorted the chart by viewership. There’s lots of information that channels take into consideration when cancelling or renewing a TV series. Ratings are usually a determining factor for ad-supported networks but they can play a smaller role for pay channels. Perception and prestige are important factors in keeping subscribers.

What do you think? Are you surprised by any of the averages? Which show(s) do you feel should be doing better or worse, based on their quality? Comment below.