| Value | Category | 
                                    
                    
                        | 0 |  | 
                                    
                    
                        | 1 | metro | 
                                    
                    
                        | 2 | bus | 
                                    
                    
                        | 3 | trolley-bus | 
                                    
                    
                        | 4 | taxi | 
                                    
                    
                        | 5 | car | 
                                    
                    
                        | 6 | bicycle,motorbike | 
                                    
                    
                        | 7 | train | 
                                    
                    
                        | 8 | donot use | 
                                    
                    
                        | 9 | other | 
                            
            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.