| Value | Category | 
                                    
                    
                        | 1 | Once a year | 
                                    
                    
                        | 2 | Twice a year | 
                                    
                    
                        | 3 | Every other year | 
                                    
                    
                        | 4 | Occasionally | 
                                    
                    
                        | 5 | This is the first time | 
                            
            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.