| Value | Category | 
                                    
                    
                        | 1 | Refused to respond | 
                                    
                    
                        | 2 | Not sure when returning | 
                                    
                    
                        | 3 | Less than 1 month | 
                                    
                    
                        | 4 | 1 month to less than 3 months | 
                                    
                    
                        | 5 | 3 months and above | 
                                    
                    
                        | 6 | Not returning | 
                            
            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.