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 | No. | Date | Championship | Surface | Opponent in the final | Score in the final |
| --- | --- | --- | --- | --- | --- | --- |
| Runner-up | 1. | 1975 | Båstad, Sweden | Clay | Manuel Orantes | 0–6, 3–6 |
| Runner-up | 2. | 1976 | São Paulo, Brazil | Carpet | Guillermo Vilas | 3–6, 0–6 |
| Winner | 1. | 1976 | Santiago, Chile | Clay | Carlos Kirmayr | 5–7, 6–4, 6–4 |
| Winner | 2. | 1977 | Murcia, Spain | Clay | Buster Mottram | 6–4, 6–0, 6–3 |
| Runner-up | 3. | 1977 | Bogotá, Colombia | Clay | Guillermo Vilas | 1–6, 2–6, 3–6 |
| Winner | 3. | 1978 | Cairo, Egypt | Clay | Kjell Johansson | 4–6, 6–4, 6–4 |
| Winner | 4. | 1978 | Nice, France | Clay | Yannick Noah | 6–3, 6–4, 6–4 |
| Runner-up | 4. | 1978 | Indianapolis, U.S. | Clay | Jimmy Connors | 0–6, 3–6 |
| Winner | 5. | 1978 | Bournemouth, England | Clay | Paolo Bertolucci | 6–2, 6–1, 6–3 |
| Winner | 6. | 1978 | Madrid, Spain | Clay | Tomáš Šmíd | 6–7, 6–3, 6–3, 6–4 |
| Winner | 7. | 1979 | Houston, U.S. | Clay | Gene Mayer | 6–3, 2–6, 7–6 |
| Winner | 8. | 1979 | Hamburg, Germany | Clay | Harold Solomon | 3–6, 6–1, 6–4, 6–1 |
| Runner-up | 5. | 1979 | North Conway, U.S. | Clay | Harold Solomon | 7–5, 4–6, 6–7 |
| Winner | 9. | 1979 | Boston, U.S. | Clay | Hans Gildemeister | 6–3, 6–1 |
| Runner-up | 6. | 1979 | Quito, Ecuador | Clay | Víctor Pecci | 6–2, 4–6, 2–6 |
| Runner-up | 7. | 1979 | Santiago, Chile | Clay | Hans Gildemeister | 5–7, 7–5, 4–6 |
| Runner-up | 8. | 1981 | Viña del Mar, Chile | Clay | Víctor Pecci | 4–6, 0–6 |
| Runner-up | 9. | 1982 | Linz, Austria | Clay | Anders Järryd | 4–6, 6–4, 4–6 |
| Winner | 10. | 1982 | Hamburg, Germany | Clay | Peter McNamara | 4–6, 6–7, 7–6, 6–3, 7–6 |
| Runner-up | 10. | 1982 | North Conway, U.S. | Clay | Ivan Lendl | 3–6, 2–6 |
| Winner | 11. | 1982 | Indianapolis, U.S. | Clay | Jimmy Arias | 7–5, 5–7, 6–3 |
| Winner | 12. | 1983 | La Quinta, U.S. | Hard | Eliot Teltscher | 6–4, 6–2 |
| Winner | 13. | 1983 | Bournemouth, England | Clay | Tomáš Šmíd | 2–6, 7–6, 7–5 |
| Runner-up | 11. | 1983 | Hamburg, Germany | Clay | Yannick Noah | 6–3, 5–7, 2–6, 0–6 |
| Runner-up | 12. | 1983 | Rome, Italy | Clay | Jimmy Arias | 2–6, 7–6, 1–6, 4–6 |
| Winner | 14. | 1983 | Stuttgart Outdoor, Germany | Clay | Heinz Günthardt | 6–1, 6–1, 7–6 |
| Winner | 15. | 1984 | Kitzbühel, Austria | Clay | Víctor Pecci | 7–5, 3–6, 6–1 |
| Winner | 16. | 1984 | Bordeaux, France | Clay | Francesco Cancellotti | 7–5, 6–1 |
Question:
how many courts are clay?
Answer:
26