| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over a period of [num] years | 97 |
|
| 2 | over a period of five years | 12 |
|
| 3 | over a period of five years | 12 |
|
| 4 | over a period of [det] years | 12 |
|
| 5 | over a period of two years | 12 |
|
| 6 | over a period of two years | 12 |
|
| 7 | over a period of three years | 8 |
|
| 8 | over a period of three years | 8 |
|
| 9 | 7 |
|
|
| 10 | over a period of several years | 7 |
|
| 11 | over a period of twenty years | 6 |
|
| 12 | over a period of twenty years | 6 |
|
| 13 | over a period of ten years | 5 |
|
| 14 | over a period of ten years | 5 |
|
