| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 | 
                                    
                                    0.8%
                                 | 
| 1 | Yes | 124 | 
                                    
                                    15.9%
                                 | 
| 2 | No | 649 | 
                                    
                                    83.3%
                                 | 
| Sysmiss | 637 |