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:
| Date | Tournament | Surface | Opponent in the final | Score |
| --- | --- | --- | --- | --- |
| 20 May 1990 | Bournemouth | Clay | Anna Benzon | 7–6, 6–1 |
| 17 May 1992 | Bournemouth | Hard | Amy Van Buuren | 6–2, 6–2 |
| 14 June 1992 | Modena | Clay | Alexandra Fusai | 6–4, 6–3 |
| 5 July 1992 | Vaihingen | Clay | Lubomira Bacheva | 6–1, 6–0 |
| 5 March 1995 | San Juan | Hard | Kyoko Nagatsuka | 7–6 5 , 6–3 |
| 20 July 1997 | Prague | Clay | Marion Maruska | 6–1, 6–1 |
Question:
What is the surface at the tournament of Vaihingen?
Answer:
Clay