Background: Joseph Guilherme Raposo, OIH (February 8, 1937 - February 5, 1989) was a Portuguese-American composer, songwriter, pianist, television writer and lyricist, best known for his work on the children's television series Sesame Street, for which he wrote the theme song, as well as classic songs such as "Bein' Green" and "C Is For Cookie". He also wrote music for television shows such as The Electric Company, Shining Time Station and the sitcoms Three's Company and The Ropers, including their theme songs. In addition to these works, Raposo also composed extensively for the DePatie-Freleng Enterprises such as Halloween Is Grinch Night, Pontoffel Pock, Where Are You? and The Grinch Grinches the Cat in the Hat.
Context: Raposo is best known for the songs he wrote for Sesame Street from its beginning in 1969 through the mid-1970s, and also for a time in the 1980s. He wrote the "Sesame Street Theme" - various versions of which have opened every episode - as well as many of its most popular songs, such as "Bein' Green", "C is for Cookie", "Sing" and "ABC-DEF-GHI". A version of "Sing" recorded by The Carpenters in 1973 reached #3 on the Billboard top singles chart. For many years, most of the music used in Sesame Street's film segments was also written -- and often sung -- by Raposo.  Aside from his musical contributions, Raposo performed several uncredited stock characters on Sesame Street during the early 1970s. According to his son Nicholas in a 2002 telephone conversation, Joe Raposo usually chose to portray anonymous, silly characters in these segments, which were nearly always produced on 16 mm film. He also did voice-overs for a few animated segments.  The Sesame Street character Don Music maintained a framed and autographed glamour photograph of Raposo on the wall of his Muppet atelier.  Raposo was very fond of sweets according to many who knew him. One favorite food of his was cookies. It has been rumored the Wheel-Eating Monster created for commercial advertisers in the 1960s by Jim Henson may have been altered by Henson specifically into a "cookie" monster after Henson observed Raposo's unusual propensity for cookies; this has never been substantiated. Raposo was actually the first puppeteer to operate Cookie Monster on television for Sesame Street. His widow Pat Collins-Sarnoff celebrated his life with a milk and cookies reception.  One of Raposo's Sesame Street compositions, "The Square Song", was used in the film Close Encounters of the Third Kind.
Question: How long did he protray cookie monster?

Answer:
1960s