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:
| Position | Team | Played | Drawn | Lost | Goals For | Goals Against | Goal Difference | Points 1 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1.0 | Stafford Rangers | 42.0 | 8.0 | 8.0 | 81.0 | 40.0 | +41 | 86 |
| 2.0 | Macclesfield Town | 42.0 | 13.0 | 6.0 | 67.0 | 39.0 | +28 | 82 |
| 3.0 | Witton Albion | 42.0 | 8.0 | 12.0 | 57.0 | 39.0 | +18 | 74 |
| 4.0 | Hyde United | 42.0 | 8.0 | 13.0 | 68.0 | 52.0 | +16 | 71 |
| 5.0 | Marine | 42.0 | 15.0 | 9.0 | 59.0 | 34.0 | +25 | 69 |
| 6.0 | Burton Albion | 42.0 | 15.0 | 9.0 | 70.0 | 49.0 | +21 | 69 |
| 7.0 | Worksop Town | 42.0 | 10.0 | 13.0 | 68.0 | 56.0 | +12 | 67 |
| 8.0 | Workington | 42.0 | 9.0 | 15.0 | 59.0 | 53.0 | +6 | 63 |
| 9.0 | Horwich RMI | 42.0 | 14.0 | 12.0 | 67.0 | 50.0 | +17 | 62 |
| 10.0 | Bangor City | 42.0 | 9.0 | 16.0 | 70.0 | 61.0 | +9 | 60 |
| 11.0 | Gainsborough Trinity | 42.0 | 14.0 | 14.0 | 72.0 | 73.0 | −1 | 56 |
| 12.0 | Southport | 42.0 | 9.0 | 18.0 | 65.0 | 66.0 | −1 | 54 |
| 13.0 | Matlock Town | 42.0 | 9.0 | 19.0 | 56.0 | 66.0 | −10 | 51 |
| 14.0 | Oswestry Town | 42.0 | 9.0 | 19.0 | 59.0 | 75.0 | −16 | 51 |
| 15.0 | Mossley | 42.0 | 9.0 | 19.0 | 45.0 | 65.0 | −20 | 51 |
| 16.0 | Goole Town | 42.0 | 11.0 | 18.0 | 60.0 | 65.0 | −5 | 50 |
| 17.0 | Rhyl | 42.0 | 14.0 | 17.0 | 52.0 | 63.0 | −11 | 47 |
| 18.0 | Morecambe | 42.0 | 14.0 | 17.0 | 51.0 | 67.0 | −16 | 47 |
| 19.0 | Chorley | 42.0 | 10.0 | 20.0 | 47.0 | 63.0 | −16 | 46 |
| 20.0 | South Liverpool | 42.0 | 15.0 | 18.0 | 43.0 | 71.0 | −28 | 42 |
| 21.0 | Grantham | 42.0 | 13.0 | 21.0 | 41.0 | 69.0 | −28 | 36 2 |
| 22.0 | Buxton | 42.0 | 6.0 | 28.0 | 38.0 | 79.0 | −41 | 30 |
Question:
When the Points 1 was 51 and the Goals Against was less than 66, what was the Goal Difference?
Answer:
−20