| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 | 
                                    
                                    0.6%
                                 | 
| 1 | Yes | 26 | 
                                    
                                    14.5%
                                 | 
| 2 | No | 152 | 
                                    
                                    84.9%
                                 | 
| Sysmiss | 223 |