| Value | Category | 
                                    
                    
                        |  | Did not work | 
                                    
                    
                        | 1 | 1 day | 
                                    
                    
                        | 2 | 2 days | 
                                    
                    
                        | 3 | 3 days | 
                                    
                    
                        | 4 | 4 days | 
                                    
                    
                        | 5 | 5 days | 
                                    
                    
                        | 6 | 6 days | 
                                    
                    
                        | 7 | 7 days | 
                                    
                    
                        | 8 | Unknown | 
                                    
                    
                        | 9 | NIU (not in universe) | 
                            
            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.