| Value | Category | 
                                    
                    
                        | 1 | 01. Mins | 
                                    
                    
                        | 2 | 02. Hours | 
                                    
                    
                        | 3 | 03. Days | 
                                    
                    
                        | 4 | 04. Weeks | 
                                    
                    
                        | 5 | 05. Mnths | 
                                    
                    
                        | 6 | 06. Years | 
                                    
                    
                        | 95 | 95. Topcode | 
                                    
                    
                        | 96 | 96. N/A | 
                                    
                    
                        | 97 | 97. Refuse | 
                                    
                    
                        | 98 | 98. DK | 
                                    
                    
                        | 99 | 99. Miss | 
                                    
                    
                        | Sysmiss |  | 
                            
            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.