user: Question: What was the date of the premiere that had a 20.9 rating?
Columns: ['Season', 'Premiere', 'Finale', 'Rank', 'Rating']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'September 22, 1976', 'May 4, 1977', '#3', '26.0']
SQL:

assistant: SELECT "Premiere" FROM "Table" WHERE "Rating" = '20.9';