It's not so much about whether it's the number 1, 2, 3 or whatever show 18-49. It's about what the actual ratings are. The ratings for the number 1 show in 18-49 in 2012 aren't nearly as high as they were for the number 1 show in 18-49 in 1998 when Friends was on the air. Viewership industry-wide is lower, because there are more alternatives now, and people watch the show in ways that don't count toward the ratings (like, on DVRs). The network makes money based on how many people are watching. You count eyeballs. The comparisons to everything else on the air are secondary. Number 1 ain't what it used to be.