Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Season | Premiere | Finale | Rank | Rating |
| --- | --- | --- | --- | --- |
| 1.0 | September 22, 1976 | May 4, 1977 | #3 | 26.0 |
| 2.0 | September 14, 1977 | May 10, 1978 | #4 (tie) | 24.4 |
| 3.0 | September 13, 1978 | May 16, 1979 | #9 | 24.9 |
| 4.0 | September 12, 1979 | May 7, 1980 | #20 (tie) | 20.9 |
| 5.0 | November 30, 1980 | June 24, 1981 | #59 | N/A |
Question:
What was the date of the premiere that had a 20.9 rating?
Answer:
September 12, 1979