| Value | Category | 
                                    
                    
                        | 01 | Month and year reported | 
                                    
                    
                        | 02 | Month and age reported, year imputed | 
                                    
                    
                        | 03 | Year and age reported, month imputed | 
                                    
                    
                        | 05 | Year reported, age and month imputed | 
                                    
                    
                        | 06 | Age reported, year and month imputed | 
                                    
                    
                        | 08 | Month reported, age and year imputed | 
                                    
                    
                        | 09 | Year and age reported, year ignored | 
                                    
                    
                        | 10 | Season and year reported | 
                                    
                    
                        | 11 | All values imputed | 
                                    
                    
                        | 99 | NIU (not in universe) | 
                                    
                    
                        | 12 | All reported, inconsistent | 
                            
            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.