instruction: List the people who voiced Yogi Bear in the 1980s.
context: From the time of the character's debut until 1988, Yogi was voiced by voice actor Daws Butler. Butler died in 1988; his last performance as Yogi was in the television film Yogi and the Invasion of the Space Bears.
  
  In 1983, a Yogi Bear balloon made its first appearance in the Macy's Thanksgiving Day Parade, becoming the final balloon that year. That same year, he appeared on a float named A Hanna-Barbera Christmas alongside many other Hanna-Barbera characters, as they cleaned up the streets of Broadway. The performance was bookended with animated segments featuring Yogi and Boo-Boo, voiced by Mel Blanc and Butler, respectively.
  
  After Butler's death in 1988, Greg Burson stepped in to perform the role; Butler had taught Burson personally how to voice Yogi as well as his other characters. Worsening alcoholism and a legal incident led to Burson's firing in 2004 and eventually his death in 2008.
  
  Yogi's current voice actor is Jeff Bergman. Bergman and Billy West also performed the character throughout the 1990s and early to mid-2000s for various Cartoon Network and Boomerang commercials and bumpers.
response: Daws Butler voiced Yogi Bear until 1988. Greg Burson took over for the rest of the 1980s.