| Value | Category | 
                                    
                    
                        | 1 | Less than 1 month | 
                                    
                    
                        | 2 | From 1 to 3 months | 
                                    
                    
                        | 3 | 3 to 6 months | 
                                    
                    
                        | 4 | From 6 to 12 months | 
                                    
                    
                        | 5 | A year or more | 
                                    
                    
                        | 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.