| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 | 
                                    
                                    0.5%
                                 | 
| -7 | Does not apply (spontaneous) | 13 | 
                                    
                                    3.2%
                                 | 
| 1 | Yes | 140 | 
                                    
                                    34.9%
                                 | 
| 2 | No | 246 | 
                                    
                                    61.3%
                                 | 
| Sysmiss | 554 |