Thursday Results:

With "1600 Penn" airing at 8:30 (an encore of the episode that aired on Dec. 17) and 9:30, NBC delivered its top-rated non-sports Thursday since November 8, as:

* The 8:30 "1600 Penn" encore matched NBC's comedy high in the slot this season.

* "The Office" earned its top rating since Nov. 8.

* The 9:30 "1600 Penn" delivered NBC's top non-sports rating in the slot since November 15.

* "30 Rock" matched its season high

* At 8 p.m. ET, "30 Rock" (1.4/4 in 18-49, 3.8 million viewers overall) matched its season high in 18-49 by scoring its highest rating since the show's season premiere on October 4. In total viewers, it's the top "30 Rock" of the season and biggest overall audience for the series since March 15, 2012. "30 Rock" was up versus its prior original by 27 percent in 18-49 (1.4 vs. 1.1 on December 6). .

* At 8:30 p.m. ET, an encore of the December 17 telecast of "1600 Penn" (1.4/4 in 18-49, 3.9 million viewers overall) matched NBC's season high with comedy in the time period and delivered NBC's biggest overall audience with comedy in the time period since March 15, 2012. The "1600 Penn" encore retained 100 percent of its 18-49 lead-in from the highest-rated "30 Rock" in three months.

* From 9-9:31 p.m. ET, "The Office" (2.2/6 in 18-49, 4.5 million viewers overall) filed its highest 18-49 and total-viewers results since November 8. "The Office" is #2 in the slot among ABC, CBS, NBC and Fox in adults 18-34, men 18-49 and men 25-54 and #1 among those networks in men 18-34. "The Office" built on its lead-in by 57 percent in 18-49 rating. Note that last season, "The Office" added an average 50 percent to these next-day "live plus same day" ratings when Nielsen reported "live plus seven day" results.

* From 9:31-10:01 p.m. ET, the regular-slot debut of "1600 Penn" (1.6/4 in 18-49, 3.9 million viewers overall) generated NBC's top non-sports rating in the slot since November 15 (1.7). The 9:30 "1600 Penn" retained 73 percent of its 18-49 lead-in from "The Office" (2.2/6), in line with the 76 percent average for slot predecessor "Parks and Recreation" ("live plus same day," originals only).

* From 10:01-11 p.m. ET, "Rock Center with Brian Williams" (1.1/3 in 18-49, 3.8 million viewers overall) scored its top results in adults 18-49, adults 25-54 and total viewers since November 15. "Rock Center" is up week to week by 38 percent in 18-49 rating (1.1 vs. 0.8), 27 percent in 25-54 (1.4 vs. 1.1) and 9 percent in total viewers (3.766 million vs. 3.456 million).

In Late-Night Metered Markets Thursday night:

* In Nielsen's 56 metered markets, household results were: "The Tonight Show with Jay Leno," 2.5/7; CBS's "Late Show with David Letterman," 2.6/7; and ABC's "Jimmy Kimmel Live," 2.7/7.

* In the 25 markets with Local People Meters, adult 18-49 Wednesday results were: "The Tonight Show with Jay Leno," 0.7/3; "Late Show," 0.7/3; and "Jimmy Kimmel Live," 1.2/6.

* From 12:35-1:05 a.m. ET Wednesday night, ABC's "Nightline" averaged a 1.7/6 in metered-market households and a 0.7/4 in 18-49 in the Local People Meters.

* Thursday season averages heading into this week were: in metered-market households, "Tonight," 2.7 rating, 7 share; "Late Show," 2.7/7; "Nightline," 3.1/7; and "Jimmy Kimmel Live," 1.6/5. In the Local People Meters, 18-49 season averages for Thursday were: "Tonight," 0.8/4; "Late Show," 0.7/3; "Nightline," 1.1/5; "Jimmy Kimmel Live," 0.6/3.

* From 12:35-1:35 a.m. ET, "Late Night with Jimmy Fallon" (1.3/5 in metered-market households) beat CBS's "Late Late Show with Craig Ferguson" (1.2/4). In the 25 markets with Local People Meters, "Late Night" (0.4/3 in 18-49) topped "Late Late Show" (0.3/2).

* At 1:35 a.m., "Last Call with Carson Daly" averaged a 0.7/3 in metered-market households with an encore and a 0.2/2 in adults 18-49 in the 25 markets with local people meters.

NOTE: All ratings are "live plus same day" from Nielsen Media Research unless otherwise indicated.