| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 10 | 
                                                                 
                                    
                                    90.9%
                                 
                                                             | 
                                                        
                    
| -8 | Refusal (spontaneous) | 1 | 
                                                                 
                                    
                                    9.1%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 343 |