| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 22 | 
                                    
                                    1.6%
                                 | 
| 1 | Yes | 426 | 
                                    
                                    30.1%
                                 | 
| 2 | No | 968 | 
                                    
                                    68.4%
                                 |