| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | over the last 30 years | 33 |
|
| 2 | in the last 30 years | 14 |
|
| 3 | during the last 30 years | 10 |
|
| 4 | for the last 30 years | 8 |
|
| 5 | of the last 30 years | 5 |
|
