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:
| No. in series | Title | Directed by | Written by | Original air date | Production code |
| --- | --- | --- | --- | --- | --- |
| 1.0 | "The Mama Who Came to Dinner" | Joel Zwick | William Bickley & Michael Warren | September 22, 1989 | 445230.0 |
| 2.0 | "Two-Income Family" | James O'Keefe | Robert Blair | September 29, 1989 | 446002.0 |
| 3.0 | "Short Story" | Joel Zwick | William Bickley & Michael Warren | October 6, 1989 | 446001.0 |
| 4.0 | "Rachel's First Date" | John Bowab | Pamela Eells & Sally Lapiduss | October 13, 1989 | 446004.0 |
| 5.0 | "Straight A's" | John Bowab | Geoff Gordon & Gordon Lewis | October 20, 1989 | 446007.0 |
| 6.0 | "Basketball Blues" | James O'Keefe | Barry Gold | November 3, 1989 | 446003.0 |
| 7.0 | "Body Damage" | James O'Keefe | Ken Kuta | November 10, 1989 | 446005.0 |
| 8.0 | "Mr. Badwrench" | John Bowab | Alan Eisenstock & Larry Mintz | November 17, 1989 | 446006.0 |
| 9.0 | "Stake-Out" | James O'Keefe | Pamela Eells & Sally Lapiduss | November 24, 1989 | 446010.0 |
| 10.0 | "False Arrest" | Peter Baldwin | Barry Gold | December 1, 1989 | 446008.0 |
| 11.0 | "The Quilt" | Peter Baldwin | David Scott Richardson | December 8, 1989 | 446009.0 |
| 12.0 | "Laura's First Date" | Richard Correll | William Bickley & Michael Warren | December 15, 1989 | 446012.0 |
| 13.0 | "Man's Best Friend" | Richard Correll | Robert Blair | January 5, 1990 | 446013.0 |
| 14.0 | "Baker's Dozen" | James O'Keefe | Ken Kuta | January 12, 1990 | 446014.0 |
| 15.0 | "The Big Reunion" | Richard Correll | Alan Eisenstock & Larry Mintz | January 19, 1990 | 446011.0 |
| 16.0 | "The Party" | Richard Correll | Ken Kuta | February 2, 1990 | 446016.0 |
| 17.0 | "The Big Fix" | Richard Correll | Pamela Eells & Sally Lapiduss | February 9, 1990 | 446017.0 |
| 18.0 | "Sitting Pretty" | Richard Correll | Ken Kuta | February 23, 1990 | 446018.0 |
| 19.0 | "In a Jam" | Richard Correll | Alan Eisenstock & Larry Mintz | March 16, 1990 | 446019.0 |
| 20.0 | "The Candidate" | James O'Keefe | Barry Gold | March 23, 1990 | 446015.0 |
| 21.0 | "Bowl Me Over" | Richard Correll | Robert Blair | April 20, 1990 | 446021.0 |
Question:
When 21 is the number in series what is the air date?
Answer:
April 20, 1990