| Value | Category | Cases | |
|---|---|---|---|
| 1 | Never | 7590 | 
                                                                 
                                    
                                    96%
                                 
                                                             | 
                                                        
                    
| 2 | Once | 150 | 
                                                                 
                                    
                                    1.9%
                                 
                                                             | 
                                                        
                    
| 3 | Several times | 164 | 
                                                                 
                                    
                                    2.1%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 5 |