| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 46 | 
                                                                 
                                    
                                    15.6%
                                 
                                                             | 
                                                        
                    
| 0 | None | 174 | 
                                                                 
                                    
                                    59.2%
                                 
                                                             | 
                                                        
                    
| 1 | 44 | 
                                                                 
                                    
                                    15%
                                 
                                                             | 
                                                        
                    |
| 2 | 11 | 
                                                                 
                                    
                                    3.7%
                                 
                                                             | 
                                                        
                    |
| 3 | 4 | 
                                                                 
                                    
                                    1.4%
                                 
                                                             | 
                                                        
                    |
| 5 | 7 | 
                                                                 
                                    
                                    2.4%
                                 
                                                             | 
                                                        
                    |
| 8 | 1 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    |
| 10 | 1 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    |
| 15 | 1 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    |
| 20 | 4 | 
                                                                 
                                    
                                    1.4%
                                 
                                                             | 
                                                        
                    |
| 62 | 1 | 
                                                                 
                                    
                                    0.3%
                                 
                                                             | 
                                                        
                    |
| Sysmiss | 287 |