| Value | 
                    Category | 
                                                                            
                                    
                    
                        | 0 | 
                        Never  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 1 | 
                        Rarely (once or twice)  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 2 | 
                        Sometimes (3 to 10 times)  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 3 | 
                        Often (more than 10 times)  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 99 | 
                        n/a  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | Sysmiss | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                            
            Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.