Even though television ratings are down this year for National Football League games, Comcast’s NBC television network still commands hefty prices from advertisers for NFL games as pro football remains among the most valuable properties on U.S. television.

On Thursday, NBC airs the first of its five “Thursday Night Football” games. The network had been asking advertisers to pay $560,000 for a 30-second spot, in line with what CBS cbs commanded for five early-season games. NBC has gotten some to pay as high as $600,000 for a spot, according to three people with direct knowledge of the negotiations.

CBS averaged 14.7 million viewers for its games, which were simulcast on the NFL’s cable network and Twitter twtr , a drop-off of 16% from last year.

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Networks have had to give free extra commercial time to advertisers to compensate for lower-than-promised ratings. This has given them fewer available spots to sell.

Still, advertiser demand has remained steady, keeping prices high. A media buyer with knowledge of negotiations said networks have been able to offset lower ratings by charging higher rates as measured by CPMs, “Cost Per Mille,” or how much an advertiser is paying to reach 1,000 people.

Ratings have been down across the board for the NFL this season, though the drop-off has been most apparent in national primetime games. The league has said the contentious U.S. presidential election campaign siphoned off viewers from football. Through the first nine weeks of the season, viewership was down 14% from last year.

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Last weekend, the first since the election, saw some noticeable upticks.

NBC’s cmcsa Sunday night game between the Seattle Seahawks and New England Patriots drew 22.5 million viewers, the most since the second week of the season and the first to outdraw last year’s equivalent game on the schedule. Fox’s late-afternoon national game between the Dallas Cowboys and Pittsburgh Steelers drew 28.9 million viewers, the highest on any network this season.

“These data points might support those who had attributed a larger part of the viewership loss to the presidential elections but it is too early to call,” said a Barclays analyst in a research report issued Thursday.

The Cowboys, Steelers and Patriots all boast large national followings and both games were nail-biters. ESPN’s Nov. 14 “Monday Night Football” game was down from the prior week.