| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over a period of [noun] | 296 |
|
| 2 | over a [noun sg] of years | 160 |
|
| 3 | over a [noun] of years | 160 |
|
| 4 | over a period of [noun pl] | 110 |
|
| 5 | [prep] a period of years | 70 |
|
| 6 | [prep] a period of years | 70 |
|
| 7 | over a period [prep] years | 62 |
|
| 8 | over a period of years | 62 |
|
| 9 | over a period of year | 62 |
|
| 10 | over a period of years | 62 |
|
| 11 | over a period of years | 62 |
|
| 12 | over [art] period of years | 62 |
|
| 13 | over a period of years | 62 |
|
| 14 | over [art] period of years | 62 |
|
| 15 | over a period [prep] years | 62 |
|
