| Value | Category | 
                                    
                    
                        | 0 | Less than one month | 
                                    
                    
                        | 1 |  | 
                                    
                    
                        | 2 |  | 
                                    
                    
                        | 3 |  | 
                                    
                    
                        | 4 |  | 
                                    
                    
                        | 5 |  | 
                                    
                    
                        | 6 |  | 
                                    
                    
                        | 7 |  | 
                                    
                    
                        | 8 |  | 
                                    
                    
                        | 9 |  | 
                                    
                    
                        | 10 |  | 
                                    
                    
                        | 12 |  | 
                                    
                    
                        | 15 |  | 
                                    
                    
                        | 16 |  | 
                                    
                    
                        | 20 |  | 
                                    
                    
                        | 24 |  | 
                                    
                    
                        | 36 |  | 
                                    
                    
                        | 48 |  | 
                                    
                    
                        | 60 | 5 years and more | 
                                    
                    
                        | 90 | Not yet solved | 
                                    
                    
                        | 98 | Don't know | 
                                    
                    
                        | 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.