| Value | Category | 
                                    
                    
                        | 1 | No difficulty walking or climbing | 
                                    
                    
                        | 2 | Some difficulty | 
                                    
                    
                        | 3 | A lot of difficulty | 
                                    
                    
                        | 4 | Cannot walk or climb at all | 
                                    
                    
                        | 8 | Don't know | 
                            
            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.