| Value | Category | 
                                    
                    
                        | 1 | Less than 1 month | 
                                    
                    
                        | 2 | 1 - 2.9 months | 
                                    
                    
                        | 3 | 3 - 5.9 months | 
                                    
                    
                        | 4 | 6 - 8.9 months | 
                                    
                    
                        | 5 | 9 - 11.9 months | 
                                    
                    
                        | 6 | More than 11.9 months | 
                                    
                    
                        | 9 | Unknown | 
                            
            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.