| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | three years ' [noun] | 146 |
|
| 2 | [adj] years ' duration | 71 |
|
| 3 | three [noun pl] ' duration | 28 |
|
| 4 | three [noun] ' duration | 28 |
|
| 5 | three year ' duration | 25 |
|
| 6 | three years ['s] duration | 25 |
|
| 7 | three years [unc] duration | 25 |
|
| 8 | three years ' duration | 25 |
|
