| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over the [adj] eighteen months | 8 |
|
| 2 | over [art] [adj] eighteen months | 8 |
|
| 3 | over [art] [adj] eighteen months | 8 |
|
| 4 | over [art] past eighteen months | 7 |
|
