| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 60 | 
                                    
                                    8.8%
                                 | 
| 1 | Yes | 68 | 
                                    
                                    10%
                                 | 
| 2 | No | 551 | 
                                    
                                    81.1%
                                 | 
| Sysmiss | 276 |