| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 | 
                                    
                                    0.7%
                                 | 
| 1 | Yes | 15 | 
                                    
                                    2.5%
                                 | 
| 2 | No | 593 | 
                                    
                                    96.9%
                                 |