The 2008 Beijing Olympics have surpassed the cumulative viewership of the 2004 Athens Summer Games, becoming the No. 3 most-watched TV event in history.

Through Tuesday night, 12 nights in, 203.3 million viewers have tuned in to some portion of the Games on NBC, putting it 700,000 better than the full draw in Athens.

NBC remains on track to pass the 1996 Atlanta Games as the most-viewed in history. That year the network attracted 209 million viewers, and Beijing is pacing 4 million ahead of Atlanta’s total through 12 days of the Games.

There are still five nights left to be counted. Wednesday night’s viewership will likely push Beijing past the No. 2 most-viewed Olympics, 1994’s Lillehammer Winter Games, which drew 203.9 million.

Viewership for the Games remains strong, if not nearly as dominating in its first week. Tuesday night NBC averaged 26.6 million total viewers in primetime, up 6 percent over the 25 million who tuned in the same night in Athens four years ago.

Among households, NBC averaged a 16.3 rating and 27 share, up 4 percent from a 15.7/26 for Athens.

The network was down on both measures versus the previous week, when the women’s gymnastics team earned a silver medal and Michael Phelps was in the pool. That night drew 34 million viewers and a 19.9/34 rating, the biggest night of the Games thus far.

But ratings traditionally slip in week two of the Games, because week one’s gymnastics and swimming are among the most popular events.

Beijing is still on track to better Athens and Sydney 2000 in both average viewers and households, as well as deliver well above the 14.5 rating NBC had promised advertisers.

Through 12 nights, the Olympics are averaging 29.3 million total viewers, up 12 percent from Athens’ 26.1 million.

NBC is averaging a 17.1/29 in households in primetime, the best for a non-U.S. Olympics since Barcelona in 1992 and 8 percent better than a 15.8/27 for Athens four years ago.

The Olympics continue to dominate the other networks in primetime. Tuesday night NBC topped ABC, CBS and Fox’s combined adults 18-49 rating by 98 percent, averaging an 8.5 to their 4.3.

Among total viewers, NBC was 90 percent ahead of the other three in primetime, averaging 25.7 million to their 13.5 million.