Fast National ratings for Tuesday, July 31, 2012.
 
With two Michael Phelps races and a big win for the US women gymnasts, it's no wonder that Tuesday night's Olympics coverage hit the week's biggest numbers for NBC.
 
Among adults 18-49, NBC averaged a 12.2 rating, just a wee bit ahead of second place CBS' 1.0 rating in the key demographic. FOX averaged a 0.9 key demo rating, while ABC posted a 0.6 key demo rating. The CW's 0.2 key demo rating trailed.
 
Overall, NBC averaged an estimated 37.49 million viewers and a 21.1 rating/33 share for Tuesday primetime. CBS was a rather distant second with a 3.7/6 and 5.44 million, still comfortably ahead of the 1.7/3 and 2.56 million viewers for ABC. FOX's 1.5/2 and 2.25 million viewers beat the 0.4/1 and 666,000 viewers for The CW.
 
8 p.m. - Predictably, NBC started primetime in first with 29.77 million viewers and a 9.0 rating among adults 18-49 for Olympics coverage. CBS' repeat of "NCIS" was second with 6.78 million viewers and a 1.0 key demo rating. ABC's repeats of "The Middle" and "Last Man Standing" averaged 2.52 million viewers and a 0.6 key demo rating, compared to the 2.33 million viewers and 1.0 key demo rating for FOX's "MasterChef" repeat. The CW's repeat of "Hart of Dixie" averaged 781,000 viewers and a 0.2 key demo rating.
 
9 p.m. - The Olympics coverage rose to 40.48 million viewers and a 13.3 rating among adults 18-49 for NBC. CBS' "NCIS: Los Angeles" repeat averaged 5.19 million viewers and a 1.0 key demo rating for second. ABC's "Wipeout" repeat averaged 2.37 million viewers and a 0.7 key demo rating compared to FOX's 2.17 million viewers and a 0.9 key demo rating for a repeat of "Hell's Kitchen." The CW's new "The L.A. Complex" averaged 550,000 viewers (up from last week!) and a 0.2 key demo rating (and a "0" key demo share). 
 
10 p.m. - NBC's final hour of Olympics coverage averaged 42.21 million viewers and a whopping 14.2 rating among adults 18-49. CBS was a distant second with 4.35 million viewers and a 0.9 key demo rating for a repeat of "Person of Interest." ABC's "NY Med" took a big drop from last week, finishing third with 2.8 million viewers and a 0.6 key demo rating.
 
All ratings information comes from preliminary Fast National Nielsen data, which includes live and same-day DVR viewing. All numbers are subject to change.