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. | Date | Location | Surface | Opponent in final | Score |
| --- | --- | --- | --- | --- | --- |
| 1. | 28 August 2000 | Spoleto, Italy $10,000 | Clay | Maret Ani | 6–2 7–6(7) |
| 2. | 9 April 2001 | San Luis Potosí, Mexico $25,000 | Clay | Martina Müller | 6–4 7–5 |
| 3. | 16 April 2001 | Coatzacoalcos, Mexico $25,000 | Hard | Gabriela Voleková | 6–1 6–3 |
| 4. | 15 October 2002 | Sedona, USA $25,000 | Hard | Brie Rippner | 6–3 4–6 6–3 |
| 5. | 5 November 2002 | Pittsburgh, USA $50,000 | Hard | Maria Sharapova | 7–6(4) 6–2 |
| 6. | 14 April 2003 | San Luis Potosí, Mexico $25,000 | Clay | Maria Vanina Garcia Sokol | 6–0 6–4 |
| 7. | 27 April 2009 | Cagnes-sur-Mer, France $100,000 | Clay | Zuzana Ondrášková | 6–1–6–2 |
| 8. | 1 June 2009 | Nottingham, England $50,000 | Grass | Stefanie Vögele | 6–2 4–6 6–1 |
Question:
what is the total number of locations that used a clay surface?
Answer:
4