| Value | Category | Cases | |
|---|---|---|---|
| 1 | Never | 7716 | 
                                                                 
                                    
                                    97.6%
                                 
                                                             | 
                                                        
                    
| 2 | Once | 89 | 
                                                                 
                                    
                                    1.1%
                                 
                                                             | 
                                                        
                    
| 3 | Several times | 99 | 
                                                                 
                                    
                                    1.3%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 5 |