It's always expected that a show drops from its series premiere. But, how much of their audiences have the new broadcast shows retained? A graph with just a few data points is actually very telling. The purple bar indicates the series premiere, the light blue indicates a ratings in the middle of its run so far, and the green indicates the most recent data point as of this publishing (Wednesday, January 6).
Only shows that premiered in the fall but are still on the air count. I'm not bothering with Wicked City, Blood & Oil, Minority Report, The Player, and Truth be Told, as none of them air anymore and are effectively cancelled. Scream Queens does count, as it still has a glimmer of hope.
ABC
As you can see, The Muppets was REALLY rejected by audiences. It's latest number was just 38% that of the premiere. Meanwhile, fellow freshmen comedy Dr Ken hit a series of 1.2s in a row despite airing on Fridays, and the chart right now might look a tiny bit deceiving based on the fact it happened to finish 2015 on a low (1.1). Finally, Quantico represents what many shows do--premiere relatively high, decline, but then level out at a respectable level.
CBS
CBS premiered four new shows in 2015, and while none really failed, you can see that they've had a wide range of results. Code Black isn't exactly at great numbers, but then again it's not doing all that much worse from its premiere. Supergirl premiered really well out of The Big Bang Theory, but fell real fast. Fortunately for the show it seems to have leveled out, or even risen. Is it enough for CBS to renew a show they don't own? We also have Limitless, which has fallen but leveled out, and Life in Pieces, which has kept a remarkable amount of its premiere audience. It's certainly being helped by The Big Bang Theory, but there's very much a possibility that the show will perform decently on its own.
The CW
The CW premiered only one new show this fall, and it's not exactly lighting the ratings world on fire. It only rises to a 0.4 average in Live+7, but at least it's stayed steady over time.
FOX
There seems to be a strikingly similar trend among all four new FOX shows--they have all leveled out rather quickly--it's just that they've leveled at much different levels. While Grandfathered and Rosewood have kept a respectable 67% and 63% of their premiere audiences, respectively, The Grinder and Scream Queens have only been able to hold on to 53%, just over half. Only Rosewood settled at numbers that aren't in danger of going fractional, but it also has Empire pre-tune (just look at the half-hours) and the fact that the only drama competition is The Mysteries of Laura going for it.
NBC
Much like ABC opened up spots after Modern Family and Scandal last season to launch two new hits, NBC opened up spots after both weekly telecasts of The Voice, leading to two successes in Blindspot and Chicago Med. Blindspot kept a respectable 61% of its premiere audience so far, and although it's no Blacklist, it's also no State of Affairs or Night Shift. And although Chicago Med has only aired a handful of episodes, it didn't take much of a post-premiere drop, and even managed to grow out of Chicago Fire during the crossover event. Heroes: Reborn, meanwhile, was sampled, but as shown by the graph didn't exactly keep much of its audience. I'm expecting a cancellation.