| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over [art] period | 991 |
|
| 2 | over a period | 682 |
|
| 3 | over a period | 681 |
|
| 4 | over the period | 309 |
|
| 5 | over the period | 309 |
|
