| Value | Category | 
                                    
                    
                        | 01 | Month, year, and day reported | 
                                    
                    
                        | 02 | Month and year reported | 
                                    
                    
                        | 03 | Month and age reported, year imputed | 
                                    
                    
                        | 04 | Year and age reported, month imputed | 
                                    
                    
                        | 05 | Year reported, age and month imputed | 
                                    
                    
                        | 06 | Age reported, year and month imputed | 
                                    
                    
                        | 07 | Month reported, age and year imputed | 
                                    
                    
                        | 08 | Year and age reported, year ignored | 
                                    
                    
                        | 09 | All values imputed | 
                                    
                    
                        | 90 | No data from individual questionnaire | 
                                    
                    
                        | 99 | NIU (not in universe) | 
                            
            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.