how many years was letterman
David Letterman: 33 Years in Latenight by the Numbers. The numbers have been crunched on David Lettermanâs 33-year run in latenight. As of his final night on May 20, Letterman will have presided over 6,028 broadcasts in latenight, counting his 1982-93 run at NBC in addition to his CBS tenure. âLate Night With David Lettermanâ had 1,810 broadcasts and ran for 595 weeks.