NBC is touting another round of fall 2012 ratings achievements after winning week four of the new season in the key 18-49 demo. The network has now won the first four weeks of the season for the first time in 10 years, based on Nielsen live-plus-same-day figures.

For the week of Oct. 8-14 NBC was up 24% from the same week last fall in viewers 18-49, averaging a 2.6 rating, up from a 2.1. Powered by strong performances for “Sunday Night Football,” “The Voice,” “Revolution” and “Grimm,” the network was also up 18% in total viewers — to 7.5 million, up from 6.4 million.

The network is reporting that its lead for the season-to-date through week four in the 18-49 demo marks the second-largest margin for any network in the past nine years.

“NBC now leads the season by 0.4 of a rating point in 18-49 (with a 3.1 season average vs. a 2.7 for #2 CBS), the second biggest lead for any network at this point in the season in the last nine years (since 2003, behind only the 0.5 lead of CBS in 2010),” the network says in its announcement. “NBC’s 3.1 is the network’s highest week-four season average in the last five years (since 2007).”

Season-to-date averages through four weeks in adults 18-49 are: NBC, 3.1 average rating/9 share; CBS, 2.7/8; ABC, 2.4/7; Fox, 2.4/7; and CW, 0.6/2.

CBS continues to hold a significant advantage in total viewers. Season-to-date averages in total viewers are: CBS, 11.3 million; ABC, 8.8 million; NBC, 8.4 million; Fox, 6.5 million; and CW, 1.4 million.