| Value | Category | Cases | |
|---|---|---|---|
| 1 | Only once | 4065 | 
                                                                 
                                    
                                    68.7%
                                 
                                                             | 
                                                        
                    
| 2 | More than once | 1704 | 
                                                                 
                                    
                                    28.8%
                                 
                                                             | 
                                                        
                    
| 9 | No response | 148 | 
                                                                 
                                    
                                    2.5%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 2616 |