| Value | Category | 
                                    
                    
                        | 1 | illiterate | 
                                    
                    
                        | 2 | read & write | 
                                    
                    
                        | 3 | less than intermediate | 
                                    
                    
                        | 4 | intermediate | 
                                    
                    
                        | 5 | higher than intermediate | 
                                    
                    
                        | 6 | university | 
                                    
                    
                        | 7 | 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.