The year 2015 is nearly in the books, but before it’s history, let’s take a trip down recent ratings memory lane. Below are the calendar year 2015 rankings in the key 18-49 demographic, per Nielsen’s “most current” ratings data set, which includes seven-day delayed viewing up through Dec. 6 of this year. After that, only live-plus-same-day numbers are available, and thus, used. 1. NBC: 2.1 2. CBS: 1.9 (tie) ABC: 1.9 (tie) 4. Fox: 1.7 5. CW: 0.7 To give those numbers some context, NBC is poised to win its second calendar year in a row, and third in four years. The network has also taken the...