| Value | Category | Cases | |
|---|---|---|---|
| 1 | Never | 7489 | 
                                                                 
                                    
                                    94.7%
                                 
                                                             | 
                                                        
                    
| 2 | Once | 230 | 
                                                                 
                                    
                                    2.9%
                                 
                                                             | 
                                                        
                    
| 3 | Several times | 185 | 
                                                                 
                                    
                                    2.3%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 5 |