| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | period of [num] years | 319 |
|
| 2 | period [prep] five years | 48 |
|
| 3 | period [prep] two years | 44 |
|
| 4 | period [prep] three years | 44 |
|
| 5 | period [prep] ten years | 17 |
|
| 6 | period [prep] four years | 16 |
|
| 7 | period [prep] twenty years | 13 |
|
| 8 | period [prep] six years | 12 |
|
| 9 | period [prep] 10 years | 11 |
|
| 10 | period [prep] seven years | 10 |
|
| 11 | period [prep] 20 years | 8 |
|
| 12 | period [prep] 15 years | 6 |
|
| 13 | period [prep] eight years | 5 |
|
| 14 | period [prep] thirty years | 5 |
|
| 15 | period [prep] fifteen years | 5 |
|
