| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| 0 | None | 1 | 
                                    
                                    50%
                                 | 
| 15 | 1 | 
                                    
                                    50%
                                 | |
| Sysmiss | 148 |