| Value | Category | 
                                    
                    
                        | 1 | Illiterate | 
                                    
                    
                        | 2 | No primary | 
                                    
                    
                        | 3 | Primary | 
                                    
                    
                        | 4 | Basic | 
                                    
                    
                        | 5 | Secondary | 
                                    
                    
                        | 6 | Vocational | 
                                    
                    
                        | 7 | Secondary specialized | 
                                    
                    
                        | 8 | University | 
                                    
                    
                        | 9 | Post-graduate | 
                                    
                    
                        | Sysmiss |  | 
                            
            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.