| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 142 | 
                                                                 
                                    
                                    12%
                                 
                                                             | 
                                                        
                    
| 0 | 785 | 
                                                                 
                                    
                                    66.2%
                                 
                                                             | 
                                                        
                    |
| 1 | 161 | 
                                                                 
                                    
                                    13.6%
                                 
                                                             | 
                                                        
                    |
| 2 | 60 | 
                                                                 
                                    
                                    5.1%
                                 
                                                             | 
                                                        
                    |
| 3 | 17 | 
                                                                 
                                    
                                    1.4%
                                 
                                                             | 
                                                        
                    |
| 5 | 10 | 
                                                                 
                                    
                                    0.8%
                                 
                                                             | 
                                                        
                    |
| 6 | 2 | 
                                                                 
                                    
                                    0.2%
                                 
                                                             | 
                                                        
                    |
| 8 | 1 | 
                                                                 
                                    
                                    0.1%
                                 
                                                             | 
                                                        
                    |
| 10 | 5 | 
                                                                 
                                    
                                    0.4%
                                 
                                                             | 
                                                        
                    |
| 15 | 1 | 
                                                                 
                                    
                                    0.1%
                                 
                                                             | 
                                                        
                    |
| 30 | 1 | 
                                                                 
                                    
                                    0.1%
                                 
                                                             | 
                                                        
                    |
| Sysmiss | 31 |