| Value | Category | Cases | |
|---|---|---|---|
| 1 | Never | 6179 | 
                                                                 
                                    
                                    78.1%
                                 
                                                             | 
                                                        
                    
| 2 | Once | 578 | 
                                                                 
                                    
                                    7.3%
                                 
                                                             | 
                                                        
                    
| 3 | Several times | 1147 | 
                                                                 
                                    
                                    14.5%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 5 |