This is another animated graph from Data Is Beautiful (previously) detailing the most popular television series from 1986 to 2019, as measure by "prime-time first 24 hours audience reports, one week of reported statistics for downloaded copies (pirated), one week of streaming services viewership. Numbers are worldwide with significant bias towards US market up until 2002, afterwards it's balanced by p2p distribution across the globe."
Interestingly, in 1986 NBC had five of the top six shows, but by 2019 doesn't have a single show in the top ten. I also learned several other things by watching it, but mostly that it's amazing how many millions of people can have such piss-poor taste in programming.
Keep going for the video while I start pitching shows to NBC.
Thanks to Christina D, who agrees the best shows of all time are Weather Center (1998 - 2009) and Weather Center Live on the Weather Channel.