| Value | Category | 
                                    
                    
                        | 0 | Never | 
                                    
                    
                        | 1 | Nhatre | 
                                    
                    
                        | 2 |  | 
                                    
                    
                        | 3 | Cap I | 
                                    
                    
                        | 4 | Cap II | 
                                    
                    
                        | 5 | Cap III | 
                                    
                    
                        | 6 | Nghe SC | 
                                    
                    
                        | 7 | THCN | 
                                    
                    
                        | 8 | DHDC | 
                                    
                    
                        | 9 | DHCD | 
                                    
                    
                        | 10 | Thac sy | 
                                    
                    
                        | 11 | PTS | 
                                    
                    
                        | 12 | TS | 
                            
            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.