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:
| Outcome | Year | Championship | Surface | Partner | Opponents | Score |
| --- | --- | --- | --- | --- | --- | --- |
| Winner | 1975.0 | French Open | Clay | Chris Evert | Julie Anthony Olga Morozova | 6–3, 6–2 |
| Winner | 1976.0 | Wimbledon | Grass | Chris Evert | Billie Jean King Betty Stöve | 6–1, 3–6, 7–5 |
| Runner-up | 1977.0 | Wimbledon | Grass | Betty Stöve | Helen Gourlay JoAnne Russell | 6–3, 6–3 |
| Winner | 1977.0 | US Open | Clay | Betty Stöve | Renee Richards Betty Ann Grubb Stuart | 6–1, 7–6 |
| Winner | 1978.0 | US Open (2) | Hard | Billie Jean King | Kerry Reid Wendy Turnbull | 7–6, 6–4 |
| Winner | 1979.0 | Wimbledon (2) | Grass | Billie Jean King | Betty Stöve Wendy Turnbull | 5–7, 6–3, 6–2 |
| Runner-up | 1979.0 | US Open | Hard | Billie Jean King | Betty Stöve Wendy Turnbull | 7–5, 6–3 |
| Winner | 1980.0 | US Open (3) | Hard | Billie Jean King | Pam Shriver Betty Stöve | 7–6, 7–5 |
| Winner | 1980.0 | Australian Open | Grass | Betsy Nagelsen | Ann Kiyomura Candy Reynolds | 6–4, 6–4 |
| Winner | 1981.0 | Wimbledon (3) | Grass | Pam Shriver | Kathy Jordan Anne Smith | 6–3, 7–6 (8–6) |
| Runner-up | 1981.0 | Australian Open | Grass | Pam Shriver | Kathy Jordan Anne Smith | 6–2, 7–5 |
| Winner | 1982.0 | French Open (2) | Clay | Anne Smith | Rosemary Casals Wendy Turnbull | 6–3, 6–4 |
| Winner | 1982.0 | Wimbledon (4) | Grass | Pam Shriver | Kathy Jordan Anne Smith | 6–4, 6–1 |
| Winner | 1982.0 | Australian Open (2) | Grass | Pam Shriver | Claudia Kohde-Kilsch Eva Pfaff | 6–4, 6–2 |
| Winner | 1983.0 | Wimbledon (5) | Grass | Pam Shriver | Rosemary Casals Wendy Turnbull | 6–2, 6–2 |
| Winner | 1983.0 | US Open (4) | Hard | Pam Shriver | Rosalyn Fairbank Candy Reynolds | 6–7 (4–7) , 6–1, 6–3 |
| Winner | 1983.0 | Australian Open (3) | Grass | Pam Shriver | Anne Hobbs Wendy Turnbull | 6–4, 6–7, 6–2 |
| Winner | 1984.0 | French Open (3) | Clay | Pam Shriver | Claudia Kohde-Kilsch Hana Mandlíková | 5–7, 6–3, 6–2 |
| Winner | 1984.0 | Wimbledon (6) | Grass | Pam Shriver | Kathy Jordan Anne Smith | 6–3, 6–4 |
| Winner | 1984.0 | US Open (5) | Hard | Pam Shriver | Anne Hobbs Wendy Turnbull | 6–2, 6–4 |
| Winner | 1984.0 | Australian Open (4) | Grass | Pam Shriver | Claudia Kohde-Kilsch Helena Suková | 6–3, 6–4 |
| Winner | 1985.0 | French Open (4) | Clay | Pam Shriver | Claudia Kohde-Kilsch Helena Suková | 4–6, 6–2, 6–2 |
| Runner-up | 1985.0 | Wimbledon | Grass | Pam Shriver | Kathy Jordan Elizabeth Smylie | 5–7, 6–3, 6–4 |
| Runner-up | 1985.0 | US Open | Hard | Pam Shriver | Claudia Kohde-Kilsch Helena Suková | 6–7, 6–2, 6–3 |
| Winner | 1985.0 | Australian Open (5) | Grass | Pam Shriver | Claudia Kohde-Kilsch Helena Suková | 6–3, 6–4 |
| Winner | 1986.0 | French Open (5) | Clay | Andrea Temesvári | Steffi Graf Gabriela Sabatini | 6–1, 6–2 |
| Winner | 1986.0 | Wimbledon (7) | Grass | Pam Shriver | Hana Mandlíková Wendy Turnbull | 6–1, 6–3 |
| Winner | 1986.0 | US Open (6) | Hard | Pam Shriver | Hana Mandlíková Wendy Turnbull | 6–4, 3–6, 6–3 |
| Winner | 1987.0 | Australian Open (6) | Grass | Pam Shriver | Zina Garrison Lori McNeil | 6–1, 6–0 |
| Winner | 1987.0 | French Open (6) | Clay | Pam Shriver | Steffi Graf Gabriela Sabatini | 6–2, 6–1 |
| Winner | 1987.0 | US Open (7) | Hard | Pam Shriver | Kathy Jordan Elizabeth Smylie | 5–7, 6–4, 6–2 |
| Winner | 1988.0 | Australian Open (7) | Hard | Pam Shriver | Chris Evert Wendy Turnbull | 6–0, 7–5 |
| Winner | 1988.0 | French Open (7) | Clay | Pam Shriver | Claudia Kohde-Kilsch Helena Suková | 6–2, 7–5 |
| Winner | 1989.0 | Australian Open (8) | Hard | Pam Shriver | Patty Fendick Jill Hetherington | 3–6, 6–3, 6–2 |
| Winner | 1989.0 | US Open (8) | Hard | Hana Mandlíková | Mary Joe Fernández Pam Shriver | 5–7, 6–4, 6–4 |
| Winner | 1990.0 | US Open (9) | Hard | Gigi Fernández | Jana Novotná Helena Suková | 6–2, 6–4 |
Question:
What is the surface when the us open is the championship in the year 1979?
Answer:
Hard