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 | 1971.0 | Australian Open | Grass | Margaret Court | Joy Emerson Lesley Hunt | 6–0, 6–0 |
| Runner-up | 1971.0 | Wimbledon | Grass | Margaret Court | Rosemary Casals Billie Jean King | 6–3, 6–2 |
| Winner | 1974.0 | Australian Open (2) | Grass | Peggy Michel | Kerry Harris Kerry Melville | 7–5 6–3 |
| Winner | 1974.0 | Wimbledon | Grass | Peggy Michel | Helen Gourlay Karen Krantzcke | 2–6, 6–4, 6–3 |
| Winner | 1975.0 | Australian Open (3) | Grass | Peggy Michel | Margaret Court Olga Morozova | 7–6, 7–6 |
| Winner | 1976.0 | Australian Open (4) | Grass | Helen Gourlay | Renáta Tomanová Lesley Turner Bowrey | 8–1 |
Question:
What was the surface during wimbledon in 1974?
Answer:
Grass