| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 | 
                                    
                                    1%
                                 | 
| 1 | Yes | 70 | 
                                    
                                    17.5%
                                 | 
| 2 | No | 327 | 
                                    
                                    81.5%
                                 | 
| Sysmiss | 554 |