NEW YORK -- NFL ratings are at their highest in 20 years.

Through the first four weeks of the season, games are drawing their best average viewership since 1989 at 17.4 million, up 14 percent from the same point in 2008. The average was 18.1 million in 1989 through four weeks.

Sunday doubleheader games this year on CBS and Fox have averaged 22.3 million viewers, which ranks as television's most-watched show on a weekly basis.

Monday night's Packers-Vikings matchup on ESPN was the most-watched show in cable TV history with 21.8 million viewers.