| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over a [num] year period | 71 |
|
| 2 | [prep] a five year period | 21 |
|
| 3 | [prep] a two year period | 19 |
|
| 4 | [prep] a three year period | 17 |
|
| 5 | for a [num] year period | 16 |
|
| 6 | [prep] a ten year period | 8 |
|
| 7 | [prep] a one year period | 8 |
|
| 8 | during a [num] year period | 6 |
|
| 9 | [prep] a 10 year period | 5 |
|
| 10 | within a [num] year period | 5 |
|
