| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 11 |
3.7%
|
| 1 | Airport | 55 |
18.6%
|
| 2 | Land border crossing | 9 |
3%
|
| 3 | Seaport or waterway | 221 |
74.7%
|
| Sysmiss | 316 |