| Value | Category | 
                                    
                    
                        | 1 | Upto 1950 | 
                                    
                    
                        | 2 | 1951-1955 | 
                                    
                    
                        | 3 | 1956-1960 | 
                                    
                    
                        | 4 | 1961-1965 | 
                                    
                    
                        | 5 | 1966-1970 | 
                                    
                    
                        | 6 | 1971-1975 | 
                                    
                    
                        | 7 | 1976-1980 | 
                                    
                    
                        | 8 | 1981 On wards | 
                                    
                    
                        | 9 | NR | 
                            
            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.