During Johnny Carson's tenure on "The Tonight Show" on NBC from 1962 to 1992, the show dominated late night ratings, and the other networks attempted late-night talk shows only sporadically. This changed with Carson's retirement, and other networks began to air their own talk show competitors, starting with "Late Show with David Letterman" on CBS in 1993. As of the current generation of U.S. hosts, late-night talk shows vary widely on their resemblance to the original variety format, with Jimmy Fallon's incarnation of "The Tonight Show" putting heavy emphasis on sketch and game segments incorporating celebrity guests (especially involving music), while "The Late Show with Stephen Colbert" has placed a larger emphasis on news satire similar to its host's previous Comedy Central late-night program "The Colbert Report" (where Colbert portrayed himself as a parody of conservative pundits).