| Value | Category | 
                                    
                    
                        | 1 | up to 3 months | 
                                    
                    
                        | 2 | 4 months to 6 months | 
                                    
                    
                        | 3 | 7 to 11 months | 
                                    
                    
                        | 4 | 1 to 2 years | 
                                    
                    
                        | 5 | 3 to 4 years | 
                                    
                    
                        | 6 | 5 or more years | 
                                    
                    
                        | 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.