Is Letterman the New King of Late Night?

Looks like David Letterman is on top of his game with the No. 1 late-night show on TV.

CBS's "Late Show with David Letterman" received the highest ratings for last week, with an average of 3.68 million viewers. An average of 2.8 million people watched "The Tonight Show."

These ratings mark the widest margin between the shows since Letterman returned from open-heart surgery in February 2000.

Conan O'Brien took over hosting "The Tonight Show" for Jay Leno in June. Despite the numbers, O'Brien still has the 18- to 49-year-old demographic, the one advertisers covet the most.

Last year during the same week, 4.6 million people watched "The Tonight Show," making the ratings drop 38 percent.

CBS chief researcher David Poltrack told The Associated Press that executives were secretly hoping for a change and that this change is happening faster than what they expected.

Rick Ludwin, NBC's top late-night executive, said that they are very pleased that younger audiences are transitioning into watching O'Brien.

On Wednesday, Letterman's show featured Paul McCartney, who returned to the Ed Sullivan Theater to perform on same stage the Beatles performed on 45 years ago when they made their American TV debut.