'Riverdale' Leads The CW to Ratings Stability in a Volatile TV Market

Every American broadcast network's average ratings were down double digits year-over-year in 2017 except one: The CW, which managed to hold steady in spite of most of its shows slipping in the key 18-35 demographic.

This is all according to numbers crunched at TVLine, where they calculated an 11% slip for NBC, 15% for CBS, 17% for ABC and 18% for FOX since this time last year.

The CW's average audience share remained the same, largely because of a massive audience gain by Riverdale and steady performances from both Supernatural and DC's Legends of Tomorrow.

A close-up look at The CW's numbers reflect dips from most of their superhero shows that are roughly in line with the diminishing audience size industry-wide as more viewers abandon traditional television for other ways of watching content. The two outliers are Supergirl, which saw its ratings fall by 25%, and Legends of Tomorrow, which had only a 5% slide.

Legends was down 5% from its Tuesday night time slot last spring, but that represents an overall gain for The CW, who suffered with No Tomorrow in the time slot following The Flash last year. This fall's Legends of Tomorrow ratings average more than double what No Tomorrow was pulling in the same time slot. The Flash is the network's biggest performer, even after a 15% slump, which makes capitalizing on its lead-in a must for The CW -- something Legends has accomplished.

Supernatural and Riverdale, which were the fifth and sixth-most watched shows on The CW in 2016, spiked to second and third this season. The midseason premiere of Supernatural, "Wayward Sisters," will serve as a backdoor pilot for a spinoff. Riverdale, too, will get a spinoff in 2018, although that one will air on Netflix.

Riverdale's surge also means that an 18% drop by Arrow -- which swapped time slots with Riverdale -- is likely less concerning for the network than it otherwise might be. To the naked eye, it looks like the 8 p.m. Wednesday time slot is easier to make a go of than Thursday at 9.

Supergirl's big drop is a big question mark, particularly since it has remained in the same time slot and has few outside factors to explain the change. The 2018 premiere, airing in just over two weeks, will finally introduce the Legion of Super-Heroes, a group of characters who have been teased since the show's first season, so it may be interesting to look at season-over-season rather than year-over-year ratings.