The AMC drama is showing signs of age in season eight, but it's still TV's biggest hit with adults 18-49.

Basic cable's crown jewel, The Walking Dead, premiered its eighth season Sunday night. And while it's ratings heyday is now behind it, the zombie drama still obliterated all but the NFL in its return.

Initial Nielsen numbers give the episode an average 11.4 million viewers, 6.5 million of them adults 18-49, which translates to a 5.0 rating in the key demo. Comparing those stats to the comparable premiere a year ago illustrates a dramatic drop, 43 percent among total viewers, but one that also isn't entirely fair. The seventh-season premiere of The Walking Dead proved to be a ratings anomaly. Thanks to interest in a cliff-hanger, it neared series highs for a live-plus-same day telecast — averaging 17 million viewers and 10.7 million adults 18-49.

The drama subsequently saw its viewership suffer from some fatigue. Though it still recoups a great deal with live-plus-three and live-plus-seven day lifts, as most scripted fare does, the seventh season went on to average a total 16.4 million viewers (10.3 million adults 18-49) once all views were factored. That marked the second consecutive season of a downward trajectory after a five-year meteoric rise that culminated in an average 20.1 million viewers (13.3 million adults 18-49) during the 2014-15 run.

At the start of this eighth season, The Walking Dead remains the highest rated scripted series on TV of sorts. While its dominance over the rest of ad-supported cable and broadcast — new leader This Is Us (NBC) is pacing ahead of The Big Bang Theory (CBS) at the start of the broadcast season — seems to remain assured, the specter of HBO's Game of Thrones looms large. The pay cable juggernaut's recently concluded seventh season averaged nearly 31 million viewers, a great majority of them adults 18-49, with all mediums tallied.

But, really, what are ratings to an outlet like HBO? Game of Thrones exists to drive subscriptions and awards attention. The Walking Dead is the very definition of advertiser bait. And it will likely remain as much for the rest of its run, even if its peak is well behind it.

As for the rest of AMC's Sunday, the network put out a particularly long episode (two hours...) of Talking Dead. It averaged 4.2 million viewers, 2.3 million of them in the key demo.

The Walking Dead (Live+7) averages over the years

Season 1

6.9 million viewers (4.8 million adults 18-49)

Season 2

9.5 million viewers (6.6 million adults 18-49)

Season 3

14.4 million viewers (9.6 million adults 18-49)

Season 4

18.4 million viewers (12.2 million adults 18-49)

Season 5

20.1 million viewers (13.3 million adults 18-49)

Season 6

18.9 million viewers (12.1 million adults 18-49)

Season 7

16.4 million viewers (10.3 million adults 18-49)