| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1296 | 
                                                                 
                                    
                                    20.3%
                                 
                                                             | 
                                                        
                    
| -7 | Does not apply (spontaneous) | 5095 | 
                                                                 
                                    
                                    79.7%
                                 
                                                             |