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 | Partner | Opponents in the final | Score in the final |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Winner | 1. | 1968 | Wimbledon, London | Grass | John Newcombe | Ken Rosewall\n Fred Stolle | 3–6, 8–6, 5–7, 14–12, 6–3 |
| Runner-up | 1. | 1968 | Hamburg, Germany | Clay | John Newcombe | Tom Okker\n Marty Riessen | 4–6, 4–6, 5–7 |
| Runner-up | 2. | 1968 | Hobart, Australia | Grass | Fred Stolle | Mal Anderson\n Roger Taylor | 5–7, 3–6, 6–4, 6–1, 4–6 |
| Runner-up | 3. | 1969 | Philadelphia WCT, U.S. | Carpet | John Newcombe | Tom Okker\n Marty Riessen | 6–8, 4–6 |
| Winner | 2. | 1969 | French Open, Paris | Clay | John Newcombe | Roy Emerson\n Rod Laver | 4–6, 6–1, 3–6, 6–4, 6–4 |
| Winner | 3. | 1969 | Wimbledon, London | Grass | John Newcombe | Tom Okker\n Marty Riessen | 7–5, 11–9, 6–3 |
| Winner | 4. | 1970 | Wimbledon, London | Grass | John Newcombe | Ken Rosewall\n Fred Stolle | 10–8, 6–3, 6–1 |
| Winner | 5. | 1970 | Louisville, U.S. | Hard | John Newcombe | Roy Emerson\n Rod Laver | 8–6, 5–7, 6–4 |
| Winner | 6. | 1971 | Australian Open, Melbourne | Grass | John Newcombe | Tom Okker\n Marty Riessen | 6–2, 7–6 |
| Winner | 7. | 1971 | Miami WCT, U.S. | Hard | John Newcombe | Roy Emerson\n Rod Laver | 7–6, 7–6 |
| Runner-up | 4. | 1971 | Chicago WCT, U.S. | Carpet | John Newcombe | Tom Okker\n Marty Riessen | 6–7, 6–4, 6–7 |
| Winner | 8. | 1971 | Rome, Italy | Clay | John Newcombe | Andrés Gimeno\n Roger Taylor | 6–4, 6–4 |
| Winner | 9. | 1971 | Tehran WCT, Iran | Clay | John Newcombe | Bob Carmichael\n Ray Ruffels | 6–4, 6–7, 6–1 |
| Runner-up | 5. | 1972 | Richmond WCT, U.S. | Carpet | John Newcombe | Tom Okker\n Marty Riessen | 6–7, 6–7 |
| Runner-up | 6. | 1972 | Philadelphia WCT, U.S. | Carpet | John Newcombe | Arthur Ashe\n Robert Lutz | 3–6, 7–6, 3–6 |
| Runner-up | 7. | 1972 | Charlotte WCT, U.S. | Clay | John Newcombe | Tom Okker\n Marty Riessen | 4–6, 6–4, 6–7 |
| Runner-up | 8. | 1972 | Las Vegas WCT, U.S. | Hard | John Newcombe | Roy Emerson\n Rod Laver | DEF |
| Winner | 10. | 1972 | St. Louis WCT, U.S. | Carpet | John Newcombe | John Alexander\n Phil Dent | 7–6, 6–2 |
| Runner-up | 9. | 1972 | Washington WCT, U.S. | Clay | John Newcombe | Tom Okker\n Marty Riessen | 6–3, 3–6, 2–6 |
| Winner | 11. | 1972 | Boston WCT, U.S. | Hard | John Newcombe | Arthur Ashe\n Robert Lutz | 6–3, 1–6, 7–6 |
| Winner | 12. | 1974 | Toronto WCT, Canada | Carpet | Raúl Ramírez | Tom Okker\n Marty Riessen | 6–3, 2–6, 6–4 |
| Runner-up | 10. | 1974 | Monte Carlo WCT, Monaco | Clay | Manuel Orantes | John Alexander\n Phil Dent | 6–7, 6–4, 6–7, 3–6 |
| Winner | 13. | 1974 | Wimbledon, London | Grass | John Newcombe | Robert Lutz\n Stan Smith | 8–6, 6–4, 6–4 |
| Runner-up | 11. | 1974 | Sydney Indoor, Australia | Hard (i) | John Newcombe | Ross Case\n Geoff Masters | 4–6, 4–6 |
| Winner | 14. | 1976 | Australian Open, Melbourne | Grass | John Newcombe | Ross Case\n Geoff Masters | 7–6, 6–4 |
| Winner | 15. | 1976 | Charlotte WCT, U.S. | Carpet | John Newcombe | Vitas Gerulaitis\n Gene Mayer | 6–3, 7–5 |
| Winner | 16. | 1977 | Australian Open, Melbourne | Grass | Arthur Ashe | Charlie Pasarell\n Erik Van Dillen | 6–4, 6–4 |
| Runner-up | 12. | 1977 | Richmond WCT, U.S. | Carpet | Ross Case | Wojtek Fibak\n Tom Okker | 4–6, 4–6 |
| Runner-up | 13. | 1977 | Toronto Indoor WCT, Canada | Carpet | Ross Case | Wojtek Fibak\n Tom Okker | 4–6, 1–6 |
| Winner | 17. | 1977 | Sydney Indoor, Australia | Hard (i) | John Newcombe | Ross Case\n Geoff Masters | 6–7, 6–3, 6–1 |
| Winner | 18. | 1978 | Sydney Indoor, Australia | Hard (i) | John Newcombe | Mark Edmondson\n John Marks | 6–4, 6–3 |
Question:
what is the total amount of opponents from the united states in the final?
Answer:
19