| Value | Category | Cases | |
|---|---|---|---|
| 0 | 130 | 
                                                                 
                                    
                                    9.3%
                                 
                                                             | 
                                                        
                    |
| 1 | Once | 955 | 
                                                                 
                                    
                                    68.2%
                                 
                                                             | 
                                                        
                    
| 2 | Several times | 244 | 
                                                                 
                                    
                                    17.4%
                                 
                                                             | 
                                                        
                    
| d | DK | 66 | 
                                                                 
                                    
                                    4.7%
                                 
                                                             | 
                                                        
                    
| r | RF | 5 | 
                                                                 
                                    
                                    0.4%
                                 
                                                             |