| Value | Category | 
                                    
                    
                        | 1 | 1. < 1 Year | 
                                    
                    
                        | 2 | 2. 1-5 years | 
                                    
                    
                        | 3 | 3. 5-17 years | 
                                    
                    
                        | 4 | 4. 18-50 years | 
                                    
                    
                        | 5 | 5. 51 years plus | 
                                    
                    
                        | 999 | 999. Don't know | 
                            
            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.