| Value | Category | 
                                    
                    
                        | 1 | 1-4 hours | 
                                    
                    
                        | 2 | 5-8 hours | 
                                    
                    
                        | 3 | 9-12 hours | 
                                    
                    
                        | 4 | More than 12 hours | 
                                    
                    
                        | 99 | N/R | 
                                    
                    
                        | 888 | Don't know | 
                                    
                    
                        | 999 | N/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.