NBC just can't seem to find a way to attract an audience, and has now finished its second week in a row under a 3.0 household rating.

In a slower week easily dominated by CBS, NBC thought its spring would be better with "The Firm" bringing in viewers. Instead, the lawyer drama based on the John Grisham novel has completely tanked, earning just a 2.0 rating/4 share this week, and is clearly on its way to cancellation.

It was easily NBC's lowest-rated show, and was almost the lowest-rated major network show. Luckily, "The Cleveland Show" on Fox had a worse week, and "The Firm" tied with "Fringe" for second smallest audience.

What will NBC need to do to find its way back? So far this season, the network is averaging a 3.4/5. That's 11 percent lower than last year, and those ratings were nothing to write home about either. It's 26 percent behind Fox as the third-place network, and even if there is a huge "The Voice" premiere after the Super Bowl as predicted, NBC doesn't really have a chance to catch up with Fox, even with a sagging "American Idol."

For there other networks, while many shows are starting to get a little spring erosion, "The Big Bang Theory" on CBS continues to grow. The show finished this week with a season-high 9.7/16, good for third place behind "American Idol" -- and really, was not too far off from snatching second. The show has been on a tear as of late, after averaging an 8.7 household rating in its first 11 episodes, it's now averaging a 9.5 household rating in its last four episodes, a boost of more than 9 percent.

That has brought the show's overall rating up to an 8.9/15, which will have a hard time competing with "Two and a Half Men," which is still boasting a 9.7/14 thanks to a 16.2/23 season premiere. But if you look at the last four episodes of "Men," there is a total different story. The show is averaging an 8.6 household rating, including a 7.8/11 it earned in its last outing.

We've said it before: "Men" may win the overall battle between these two shows as the top comedy, but the crown more deservedly goes to "Big Bang Theory."

The new Rob Schneider comedy "Rob" is enjoying some staying power. A lighter television lineup ahead of February sweeps allowed it to stay in the top 10, and the show is staying mostly stable. It premiered with a 7.9/12 on Jan. 12, but has averaged a 6.9/10 ever since, earning a 6.7/10 this week. The biggest drawback of those numbers, however, is that it's losing more than 20 percent of its "Big Bang" lead-in audience. But then again, this is "Big Bang."

"Person of Interest" is also building audience for CBS. In its first 10 episodes, it averaged a 7.7 household rating. However, in the last three, that has grown 16 percent to an 8.9. It's even beginning to outpace "The Mentalist," which still remains strong for CBS despite an 8 percent drop in audience compared to last year.

"Grey's Anatomy" was the top show for ABC with a 6.3/10 while "Big Bang Theory" led CBS with a 9.7/16. "American Idol" topped Fox with a 10.5/17 while the best of NBC was "The Biggest Loser" with a 4.0/6. "Vampire Diaries" was the leader at The CW with a 1.8/3.

For the year so far, CBS leads with a 7.6/12, followed by ABC with a 5.8/9, Fox with a 4.6/7, NBC with a 3.4/5 and The CW with a 1.2/2.

CBS and ABC were both up slightly from this time last year, while Fox, NBC and The CW were all down significantly. NBC was off 28 percent from its audience last year, while Fox was down 24 percent and The CW down 21 percent.

Top Networks, Week of Jan. 29 -- [Audience Loyalty Index rating]

Top Network Shows, Week of Jan. 29 -- [ALI]

Top New Shows, Week of Jan. 29 -- [ALI]

Least-Watched Big Four Network Shows, Week of Jan. 29 -- [ALI]

Fast Nationals usually provide a snapshot of what Americans are watching by pulling numbers from the top urban markets that include both live viewing and same-day timeshifted viewing. A rating point generally represents more than 1.1 million households while the share indicates the percentage of televisions turned on that was tuned to the specific program. These numbers typically shift when final ratings are issued.

Data collected from The Nielsen Co., as distributed by Zap2it. GenreNexus tracks non-news, non-event programming, and figures for this story reflect airing of new episodes only. For more information on the Audience Loyalty Index, click here.