In another indication of changing viewing habits, shows are capturing viewers up to five weeks after they air.

Most of a given show's audience comes in the first three days after it airs. Even in a world of 500 scripted shows, most viewers get to a show within 72 hours.

Numbers back that up: In 2018-19, broadcast series collected more than 90 percent of their seven-day viewer totals within the first three days. After that, the audience tails off — but, data from Nielsen shows, it doesn't stop. The Peak TV era has shown that series can leave a ratings footprint more than a month after it airs.

Nielsen measures viewing out to 35 days — five weeks — after a show's initial airdate. Those additional four weeks don't bring huge ratings bumps the way three- and seven-day figures can; they do, in fact, continue to move the needle.

The effect is more pronounced among adults 18-49, the demographic group advertisers pay a premium to reach, than it is among viewers as a whole. Per Nielsen, primetime dramas in the fourth quarter of 2018 rose 60 percent among adults 18-49 after 35 days, and comedies grew by 36 percent. In both cases, those gains outpaced the total-viewer lifts, which were 45 percent for dramas and 23 percent for comedies.

The Hollywood Reporter also compared seven-day and 35-day viewer averages for 20 high-performing shows from January to August 2019. On average, those shows brought in almost 1 million more viewers in days 8-35, a gain of just over 9 percent from where they stood after a week.

From initial airing to 35 days out, the 20 shows — 17 broadcast network dramas including This Is Us, The Rookie and NCIS, plus comedies The Big Bang Theory and Young Sheldon and Paramount Network breakout Yellowstone — grew by an average of 85 percent, adding an average of 5.1 million viewers. ABC's The Good Doctor had the largest lift on the list, growing by 7.05 million viewers (about 1.1 million of which came after day seven).

The Big Bang Theory's final season had the largest audience at all three Nielsen benchmarks, going from 13.67 million same-day viewers to 18 million after seven days and topping 20 million (20.07 million, to be precise) after five weeks. The CBS comedy's 2.07 million viewer gain in weeks two through five was also the largest on the list.

Six series — The Good Doctor, The Rookie, Yellowstone and NBC's Manifest, New Amsterdam and The Blacklist — at least doubled their total audiences over 35 days. The first eight episodes of Yellowstone's second season almost tripled, going from 2.29 million viewers for initial airings to 6.51 million after 35 days.

Below are the 20 shows with the biggest 35-day viewing gains from January to August 2019.

Show Network Live-plus-same-day viewers (000s) Live-plus-35 viewers (000s) Change after 35 days Percent change after 35 days The Good Doctor ABC 6,524 13,575 7,051 108% This Is Us NBC 7,778 14,520 6,742 87% Manifest NBC 5,543 11,959 6,416 116% The Big Bang Theory CBS 13,679 20,068 6,389 47% New Amsterdam NBC 5,383 11,442 6,059 113% Bull CBS 6,640 12,117 5,477 82% Blue Bloods CBS 8,322 13,600 5,278 63% Chicago PD NBC 7,134 12,089 4,955 69% The Rookie ABC 3,940 8,889 4,949 126% 911 FOX 5,901 10,794 4,893 83% NCIS CBS 12,080 16,966 4,886 40% Criminal Minds CBS 4,680 9,169 4,489 96% Young Sheldon CBS 11,404 15,887 4,483 39% FBI CBS 8,897 13,368 4,471 50% SEAL Team CBS 4,607 9,009 4,402 96% NCIS: New Orleans CBS 6,932 11,280 4,348 63% Chicago Fire NBC 8,196 12,504 4,308 53% Yellowstone Paramount 2,291 6,514 4,223 184% The Blacklist NBC 3,919 8,103 4,184 107% SWAT CBS 5,372 9,411 4,039 75%

Source: Nielsen, Jan. 1-Aug. 18, 2019