Question: Ed is an NBC television program co-produced by an American television comedian, writer, and producer who hosted a late night television talk show for how long?

Context paragraphs:
Last Call with Carson Daly: Last Call with Carson Daly is an American late night television program hosted by Carson Daly and broadcast on NBC.  Formerly a traditional talk show, the half-hour program consists of several produced segments, featuring interviews with musicians, comedians, actors, filmmakers, and other artists, along with pre-taped on-location musical performances.  It debuted in 2002.  Unlike other programs in NBC's late night line-up, "Last Call" typically records only 24 weeks of original shows a year with the rest of the year being taken up by reruns.

The NightCap: The NightCap was an Australian television talk show broadcast on 7HD.  It was the first Australian television program to be produced exclusively for a HDTV multichannel.  The show began broadcasting on the 12 February 2008 and screened every Tuesday and Thursday night at 10.30pm.  It was cancelled after the Easter 2008 television non-ratings period.  According to producer Adam Boland, he NightCap was a late night panel show that would cover news in an 'unconventional' way.

Steve Allen: Stephen Valentine Patrick William Allen (December 26, 1921 – October 30, 2000) was an American television personality, radio personality, musician, composer, actor, comedian, writer, and advocate of scientific skepticism.  He achieved national fame as the first host of "The Tonight Show", the first late night television talk show in September 1954.

The Last Leg: The Last Leg (known during its first series as The Last Leg with Adam Hills) is a British comedy and late night television talk show that originally ran alongside the 2012 Summer Paralympics every night following the main coverage on Channel 4.  Hosted by Australian comedian Adam Hills and co-hosted by Josh Widdicombe and Alex Brooker, it gave an alternative review of the day's events.

Ed (TV series): Ed is an NBC television program co-produced by David Letterman's Worldwide Pants Incorporated, NBC Productions and Viacom Productions that aired from 2000 to 2004.  The hour-long comedy-drama starred Tom Cavanagh as Edward Jeremy Stevens, the title character, Julie Bowen as his love interest Carol Phyllis Vessey, Josh Randall as his friend Dr. Mike Burton, Jana Marie Hupp as Mike's wife Nancy, Lesley Boone as their friend Molly Hudson, and Justin Long as awkward high-school student Warren Cheswick.  Other supporting cast members included Michael Genadry and Ginnifer Goodwin as Warren's friends Mark and Diane, and Michael Ian Black, Mike Starr, Rachel Cronin, and (later) Daryl Mitchell as the employees of Stuckeybowl, Ed's bowling alley.  Long term guest stars included John Slattery as Dennis Martino and Sabrina Lloyd as Frankie Hector.  The show was created by executive producers Jon Beckerman and Rob Burnett.  David Letterman is also credited as one of the show's executive producers.

Tonight Starring Steve Allen: Tonight Starring Steve Allen was a talk show hosted by Steve Allen.  It was the first version of what eventually became known as "The Tonight Show".  "Tonight" was the first late-night talk show, as well as the first late night television series of any time to achieve long-term success.  Allen's run as host of the show lasted for two and a half seasons, beginning in fall 1954 and ending with Allen's departure in January 1957.

Porta a Porta: Porta a Porta (literally "Door-to-door") is an Italian late night television talk show hosted by the Italian journalist Bruno Vespa and is broadcast on Rai Uno since 1996.  Its first episode on January 22, 1996.

David Letterman: David Michael Letterman (born April 12, 1947) is an American television host, comedian, writer, and producer.  He hosted a late night television talk show for 33 years, beginning with the February 1, 1982 debut of "Late Night with David Letterman" on NBC, and ending with the May 20, 2015 broadcast of "Late Show with David Letterman" on CBS.  In total, Letterman hosted 6,028 episodes of "Late Night" and "Late Show", surpassing friend and mentor Johnny Carson as the longest-serving late night talk show host in American television history.  In 1996 Letterman was ranked 45th on "TV Guide"' s 50 Greatest TV Stars of All Time.

The Las Vegas Show: The Las Vegas Show is an American late night television program broadcast in May 1967 on the short-lived United Network.  The two-hour-long talk show, hosted by comedian Bill Dana, was supposed to be the flagship program of a planned fourth television network.

Italia domanda: Italia domanda (literally "Italy question") is an Italian late night television talk show hosted by the Italian journalist Cesara Buonamici and is broadcast on Canale 5 since 2013.

Supporting paragraphs: Ed (TV series) David Letterman
Answer: 33 years