| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 | 
                                                                 
                                    
                                    3.2%
                                 
                                                             | 
                                                        
                    
| 0 | 32 | 
                                                                 
                                    
                                    33.7%
                                 
                                                             | 
                                                        
                    |
| 20 | 3 | 
                                                                 
                                    
                                    3.2%
                                 
                                                             | 
                                                        
                    |
| 25 | 53 | 
                                                                 
                                    
                                    55.8%
                                 
                                                             | 
                                                        
                    |
| 30 | 3 | 
                                                                 
                                    
                                    3.2%
                                 
                                                             | 
                                                        
                    |
| 40 | 1 | 
                                                                 
                                    
                                    1.1%
                                 
                                                             | 
                                                        
                    |
| Sysmiss | 293 |