| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 16 | 
                                    
                                    0.6%
                                 | 
| 1 | Yes | 494 | 
                                    
                                    18.3%
                                 | 
| 2 | No | 2187 | 
                                    
                                    81.1%
                                 |