At some point, a television sensation becomes just another show. The numbers illustrate how that's become the case with AMC's drama, "The Walking Dead."

The zombies are taking a break at the halfway point of their ninth season, following an episode on Sunday that was seen by 5.1 million people. The Nielsen company said that at a similar point last year, the midseason finale reached 7.9 million people.

For the first seven episodes of the season, the show's viewership was down 23 percent compared with last year for people who watched on the night of its premiere, and down 21 percent when people who record it and watch within three days are taken into account, Nielsen said. Increasing numbers of the show's fans, particularly younger ones, are waiting a couple of days to see a new episode.

The high point for "The Walking Dead" was its seventh season opener, seen by 21 million people.

AMC acknowledges the drop in popularity, which is hardly unusual for television shows as they age. The network says it is hard for "The Walking Dead" to compete with the ratings standard set when it was a cultural touchstone, but that it's still television's second-ranked drama behind NBC's "This is Us" among youthful viewers.

The network is also encouraged that the show survived the departure of star Andrew Lincoln earlier this season without a major drop in viewership. New episodes for "The Walking Dead" begin again in February.

Nielsen said 23.7 million people watched coverage of the Macy's Thanksgiving Day parade in New York, making it the most popular entertainment program on television since the Oscars. The absence of longtime host Matt Lauer, fired from NBC's "Today" show because of sexual misconduct shortly after the parade last year, made little difference to viewers. Last year's show was seen by 24.1 million. NBC's parade coverage was hosted by Savannah Guthrie, Hoda Kotb and Al Roker this year.

Football dominated the primetime ratings over Thanksgiving week, giving NBC a big edge. NBC averaged 9.1 million viewers, CBS had 6.4 million, ABC had 4.6 million, Fox had 2.9 million, ION Television had 1.5 million, Univision had 1.2 million, Telemundo had 1.1 million and the CW had 1 million.

ESPN was the week's most popular cable network, averaging 4.3 million in prime time. Hallmark averaged 2.67 million, Fox News Channel had 1.55 million, MSNBC had 1.19 million and USA had 1.13 million.

NBC's "Nightly News" topped the evening newscasts with an average of 9.2 million viewers. ABC's "World News Tonight" was second with 8.9 million and the "CBS Evening News" had 6.5 million viewers.

Below are primetime viewership numbers compiled by Nielsen for Nov. 19-25. Listings include the week’s ranking and viewership.

1. “NFL Post-Game Show,” Fox, 23.36 million.
2. NFL Football: Atlanta at New Orleans, NBC, 21.73 million.
3. NFL Football: Green Bay at Minnesota, NBC, 20.44 million.
4. NFL Football: Kansas City at L.A. Rams, ESPN, 16.89 million.
5. “NFL Pre-Game Show” (Thursday), NBC, 15.33 million.
6. “NFL Pre-Game Show” (Sunday), NBC, 14.17 million.
7. “60 Minutes,” CBS, 12.96 million.
8. “NCIS,” CBS, 11.95 million.
9. “Football Night in America,” NBC, 10.71 million.
10. “NFL Pre-Game Show, Part 2” (Thursday), NBC, 9.6 million.
11. “FBI,” CBS, 8.92 million.
12. “The Voice” (Tuesday), NBC, 8.23 million.
13. “God Friended Me,” CBS, 8.09 million.
14. “This is Us,” NBC, 7.92 million.
15. “The Voice” (Monday), NBC, 7.884 million.
16. “Dancing With the Stars,” ABC, 7.883 million.
17. College Football: Notre Dame at USC, ABC, 7.74 million.
18. “NCIS: New Orleans,” CBS, 7.47 million.
19. “Football Night in America, Part 2,” NBC, 7.32 million.
20. “NCIS: Los Angeles,” CBS, 7.2 million.

ABC and ESPN are owned by The Walt Disney Co.; CBS is a division of CBS Corp.; Fox is owned by 21st Century Fox; NBC is owned by NBC Universal.