| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 38 | 
                                                                 
                                    
                                    14.1%
                                 
                                                             | 
                                                        
                    
| 0 | 215 | 
                                                                 
                                    
                                    79.6%
                                 
                                                             | 
                                                        
                    |
| 10 | 2 | 
                                                                 
                                    
                                    0.7%
                                 
                                                             | 
                                                        
                    |
| 20 | 2 | 
                                                                 
                                    
                                    0.7%
                                 
                                                             | 
                                                        
                    |
| 30 | 4 | 
                                                                 
                                    
                                    1.5%
                                 
                                                             | 
                                                        
                    |
| 45 | 1 | 
                                                                 
                                    
                                    0.4%
                                 
                                                             | 
                                                        
                    |
| 50 | 4 | 
                                                                 
                                    
                                    1.5%
                                 
                                                             | 
                                                        
                    |
| 60 | 1 | 
                                                                 
                                    
                                    0.4%
                                 
                                                             | 
                                                        
                    |
| 80 | 1 | 
                                                                 
                                    
                                    0.4%
                                 
                                                             | 
                                                        
                    |
| 100 | 2 | 
                                                                 
                                    
                                    0.7%
                                 
                                                             | 
                                                        
                    |
| Sysmiss | 311 |