Which long-running NBC sketch comedy show premiered in 1975?

Who created 'The Muppet Show'? Which children's TV host famously wore cardigan sweaters and sang "Won't You Be My Neighbor?" Which TV painter was known for his "happy little trees"? Which children's series featured host LeVar Burton encouraging kids to read? Who created 'Saturday Night Live'? Who hosted 'The Tonight Show' from 1962 to 1992? Who succeeded Johnny Carson as host of 'The Tonight Show' in 1992? Who hosted 'The Late Show' on CBS from 1993 to 2015?