But it's not really comparable. TNG was first-run syndication, where the competition was considerably less than it would be in a network prime-time slot. TNG, like TOS, never cracked the top 30 in ratings, and it is highly doubtful it would have lasted as long as it did on one of the big four broadcast networks.
That's not entirely accurate, though. During TNG's real heydey, around the time of the 5th and 6th seasons, it was pulling in ratings that went head-to-head with its network competition. In particular, I remember Paramount being very proud of the fact that TNG was beating the ratings for Monday Night Football.
So, what's not accurate? There's no way to really compare TNG head-to-head with network competition because it aired at different times all over the country. And there is no reason to assume that TNG would have made it to a 5th or 6th season in network prime time. Maybe, but it would be a lot harder than in syndication, where it was the dominant property in the market.