Fast National ratings for Friday, December 28, 2012.
 
It's hard to know exactly why, but a two-hour encore of "Dateline" drew some of the newsmagazine's biggest numbers of the entire season and helped NBC lead a repeat-heavy Friday in all measures.
 
Among adults 18-49, NBC averaged a 1.4 rating for Friday night, tops in the key demographic. ABC was second with a 1.1 rating, followed by CBS' 1.0 rating and the 0.8 key demo rating for FOX. The CW did a 0.2 key demo rating for Friday primetime.
 
Overall, NBC averaged an estimated 5.44 million viewers and 3.6 rating/6 share, nipping the 3.4/6 and 5.33 million viewers for ABC on the night. CBS was third with a 3.0/5 and 4.56 million viewers. FOX was a distant fourth with a 1.4/2 and 2.345 million viewers, at least beating the 0.7/1 and 1.06 million viewers for The CW.
 
8 p.m. - CBS marathoned "Undercover Boss" repeats on Friday and won the 8 p.m. hour with 5.47 million viewers and finished second with a 1.1 rating among adults 18-49. ABC's repeat of "Shark Tank" was a close second overall with 5.41 million viewers and won the hour with a 1.4 key demo rating. FOX's encores of "How To Train Your Dragons" and "Ice Age" Christmas specials averaged 2.78 million viewers and a 0.9 key demo rating for third, topping the 2.67 million viewers and 0.8 key demo rating for repeats of "Go On" on NBC. The CW got 999,000 viewers and a 0.2 key demo rating for a repeat of "Nikita."
 
9 p.m. - "Dateline NBC," a repeat of a Josh Mankiewicz report on a kidnapping in Florida, averaged nearly 5.9 million viewers and a 1.5 rating among adults 18-49 to lead the 9 p.m. hour. ABC's "Back To The Beginning with Christiane Amanpour" was second with 5.26 million viewers and tied for second with a 1.0 key demo rating. CBS' "Undercover Boss" repeat drew 4.41 million viewers and a 1.0 key demo rating in third. FOX's repeat of "Kitchen Nightmares" drew 1.91 million viewers and a 0.7 key demo rating, topping the 1.11 million viewers and 0.3 key demo rating for The CW's "Arrow Repeat."
 
10 p.m. - NBC's "Dateline" was up to 7.76 million viewers and a 1.9 rating among adults 18-49 to rule the 10 p.m. hour. ABC's  "Back To The Beginning with Christiane Amanpour" was a distant second with 5.33 million viewers and a 0.9 key demo rating. CBS' third "Undercover Boss" repeat also had a 0.9 key demo rating and averaged 3.79 million viewers for third.
 
All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.