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 | Tournament | Winning score | Margin\nof victory | Runner(s)-up |
| --- | --- | --- | --- | --- | --- |
| 1 | Jul 18, 1982 | Miller High Life QCO | −12 (68-66-65-69=268) | 2 strokes | Brad Bryant, Pat McGowan |
| 2 | Oct 23, 1983 | Walt Disney World Golf Classic | −19 (69-64-69-67=269) | 2 strokes | Nick Faldo, Mark McCumber |
| 3 | Mar 15, 1987 | Hertz Bay Hill Classic | −20 (69-67-63-65=264) | 3 strokes | David Frost |
| 4 | Apr 16, 1989 | MCI Heritage Golf Classic | −16 (65-67-67-69=268) | 5 strokes | Kenny Perry |
| 5 | Aug 13, 1989 | PGA Championship | −12 (74-66-69-67=276) | 1 stroke | Andy Bean, Mike Reid,\n Curtis Strange |
| 6 | Apr 15, 1990 | MCI Heritage Golf Classic | −8 (70-69-66-71=276) | Playoff | Steve Jones, Larry Mize |
| 7 | May 6, 1990 | GTE Byron Nelson Golf Classic | −8 (67-68-67=202)^ | 2 strokes | Lanny Wadkins |
| 8 | Jun 17, 1991 | U.S. Open | −6 (67-70-73-72=282) | Playoff | Scott Simpson |
| 9 | Apr 30, 1995 | Shell Houston Open | −12 (73-65-70-68=276) | Playoff | Scott Hoch |
| 10 | Feb 7, 1999 | AT&T Pebble Beach National Pro-Am | −10 (69-64-73=206)^ | 1 stroke | Frank Lickliter II |
| 11 | Jun 20, 1999 | U.S. Open | −1 (68-69-72-70=279) | 1 stroke | Phil Mickelson |
Question:
what was the best winning score?
Answer:
−20 (69-67-63-65=264)