| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 57 | 
                                                                 
                                    
                                    66.3%
                                 
                                                             | 
                                                        
                    
| -8 | Refusal (spontaneous) | 29 | 
                                                                 
                                    
                                    33.7%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 312 |