| Value | Category | Cases | |
|---|---|---|---|
| 1 | Spontaneous | 73 |
63.5%
|
| 2 | Artificial | 13 |
11.3%
|
| 8 | Don't know | 26 |
22.6%
|
| 9 | No response | 3 |
2.6%
|
| Sysmiss | 6 |