| Value | Category | 
                                    
                    
                        | Just completed matrices.  wasn't working |  | 
                                    
                    
                        | Too young to study |  | 
                                    
                    
                        | still a baby |  | 
                                    
                    
                        | still a little baby |  | 
                            
            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.