| Value | Category | 
                                    
                    
                        | 1 | primary | 
                                    
                    
                        | 2 | post-primary/ vocational | 
                                    
                    
                        | 3 | secondary/ a-level | 
                                    
                    
                        | 4 | college (middle level) | 
                                    
                    
                        | 5 | university | 
                            
            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.