| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 25 | 
                                                                 
                                    
                                    32.5%
                                 
                                                             | 
                                                        
                    
| 0 | 35 | 
                                                                 
                                    
                                    45.5%
                                 
                                                             | 
                                                        
                    |
| 10 | 2 | 
                                                                 
                                    
                                    2.6%
                                 
                                                             | 
                                                        
                    |
| 15 | 1 | 
                                                                 
                                    
                                    1.3%
                                 
                                                             | 
                                                        
                    |
| 20 | 12 | 
                                                                 
                                    
                                    15.6%
                                 
                                                             | 
                                                        
                    |
| 30 | 1 | 
                                                                 
                                    
                                    1.3%
                                 
                                                             | 
                                                        
                    |
| 70 | 1 | 
                                                                 
                                    
                                    1.3%
                                 
                                                             | 
                                                        
                    |
| Sysmiss | 156 |