The Nielsen verdict is in: The People v. O.J. Simpson was a massive ratings success for FX. Last week’s finale of the Ryan Murphy–produced docudrama averaged 6.2 million viewers, including audiences who watched within three days of its Tuesday premiere. That’s a six-week high for the show, but it’s only part of the picture. FX says the series averaged 7.5 million viewers during the first two months of its run, including audiences who watched episodes within a week of their premiere. And if you count people who’ve watched reruns of the show or caught up via VOD and streaming, the network estimates just under 13 million viewers on average made O.J. a regular habit, a number it expects to hold — or increase — once viewership for the remaining episodes is tallied. O.J. has done particularly well with the younger viewers advertisers covet: So far this year, it stands as the No. 6 prime time show on all of TV (broadcast and cable) among adults under 35, and No. 8 with adults under 50. It’s also the most-watched first-season series in FX’s 22-year history. Now if Murphy and FX could only figure out some way to do an O.J. sequel …