| Value | Category | 
                                    
                    
                        | 1 | less than 1 hour | 
                                    
                    
                        | 2 | 1-2 hours | 
                                    
                    
                        | 3 | 3-5 hours | 
                                    
                    
                        | 4 | more than 5 hours | 
                                    
                    
                        | 8 | not admin. | 
                                    
                    
                        | 9 | missing | 
                                    
                    
                        | 11 | .A | 
                            
            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.