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 | Opponent in the final | Score in the final |
| --- | --- | --- | --- | --- | --- |
| Runner-up | 1973.0 | Monte-Carlo | Clay | Ilie Năstase | 4–6, 1–6, 2–6 |
| Runner-up | 1973.0 | Stockholm | Hard | Tom Gorman | 3–6, 6–4, 6–7 |
| Winner | 1974.0 | Rome | Clay | Ilie Năstase | 6–3, 6–4, 6–2 |
| Winner | 1974.0 | Boston | Clay | Tom Okker | 7–6, 6–1, 6–1 |
| Winner | 1975.0 | Boston | Clay | Guillermo Vilas | 6–3, 6–4, 6–2 |
| Winner | 1976.0 | Boston | Clay | Harold Solomon | 6–7, 6–4, 6–1, 6–2 |
| Runner-up | 1976.0 | Philadelphia | Carpet | Jimmy Connors | 6–7, 4–6, 0–6 |
| Winner | 1977.0 | Monte Carlo | Clay | Corrado Barazzutti | 6–3, 7–5, 6–0 |
| Winner | 1977.0 | London | Carpet | John Lloyd | 6–4, 6–4, 6–3 |
| Winner | 1978.0 | Tokyo | Carpet | Brian Teacher | 6–3, 6–4 |
| Winner | 1978.0 | Rome | Clay | Adriano Panatta | 1–6, 6–3, 6–1, 4–6, 6–3 |
| Winner | 1979.0 | Tokyo | Carpet | Jimmy Connors | 6–3, 6–2 |
| Winner | 1979.0 | Monte Carlo | Clay | Vitas Gerulaitis | 6–2, 6–1, 6–3 |
| Winner | 1979.0 | Toronto | Hard | John McEnroe | 6–3, 6–3 |
| Winner | 1979.0 | Las Vegas | Hard | Jimmy Connors | 6–3, 6–2 |
| Winner | 1980.0 | Monte Carlo | Clay | Guillermo Vilas | 6–1, 6–0, 6–2 |
| Runner-up | 1980.0 | Toronto | Hard | Ivan Lendl | 4–6, 5–4, ret. |
| Winner | 1980.0 | Stockholm | Hard | John McEnroe | 6–3, 6–4 |
Question:
Name the year for clay for boston and guillermo vilas
Answer:
1975.0