| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 | 
                                    
                                    0.7%
                                 | 
| -7 | Does not apply (spontaneous) | 16 | 
                                    
                                    4%
                                 | 
| 1 | Yes | 95 | 
                                    
                                    23.7%
                                 | 
| 2 | No | 287 | 
                                    
                                    71.6%
                                 | 
| Sysmiss | 554 |