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David Letterman's Late Show by the numbers

Jen Rogers

As everyone's favorite gap toothed comedian retires, we thought we'd take a look at David Letterman by the numbers.

Letterman's morning show only lasted 4 months back in 1980. His late night career has been much more long-lived. In fact, he's now the longest serving late night host in history. When all is said and done, David Letterman will have done 6,028 broadcasts of his two late-night shows on both NBC and CBS. Letterman has hosted a total 19,932 guests, according to CBS. Marv Albert had the most guest appearances on NBC's "Late Night" with 73; while Regis Philbin can claim the crown on the CBS "Late Show" with over 100. Since it's debut in September 1985, there have been 5,614 Top Ten Lists. The very first one was, “Things That Almost Rhyme With Peas."

From Top Ten Lists to Stupid Pet Tricks, David Letterman's The Late Show was distinctly his own in more ways than one. Like Johnny Carson before him, Letterman actually owned his show on CBS, which helped make him a very rich man. By most estimates he's worth at least $400 million dollars. His salary on CBS's The Late Show is believed to be around $20 million and that's down from a reported $30 million or more at its height. And that’s just one revenue stream for the iconic comedian. His production company Worldwide Pants is still reaping millions in syndication fees from its big hit "Everybody Loves Raymond."

According to Ad Age, in 2009 The Late Show pulled in $271 million in advertising revenue, almost $100 million more than Jay Leno's Tonight show at the time. But with the late night landscape fragmenting and cable pulling in more of the young viewers advertisers want, ratings and revenues have been a struggle for The Late Show. While Letterman was a comfortable second to Leno in the ratings race for years, he recently slipped to third behind Jimmy Kimmel and Jimmy Fallon in the key 18-49 demographic and that's had an impact on the bottom line. Kantar Media research shows that Late Show revenue was $114.5 million in 2014, down from $129.6 million in 2013.

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With ratings and ad revenue falling the last few years, Letterman's late night math is getting fuzzier. While the Late Show is understood to be profitable, the onslaught of new social media darlings like Kimmel and Fallon get all the attention. The bottom line to TV executives may be a number some see as a more valuable metric than money. Jimmy Fallon has over 25 million Twitter followers, Jimmy Kimmel has 5.2 million and Letterman has only 330,000.

But when it gets down to it, the only number that really matters are the countless laughs delivered over the decades.

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