| Value | Category | 
                                    
                    
                        | 1 | Private car | 
                                    
                    
                        | 2 | Motocycle | 
                                    
                    
                        | 3 | Public bus | 
                                    
                    
                        | 4 | Taxi | 
                                    
                    
                        | 5 | Robot | 
                                    
                    
                        | 6 | Bicycle | 
                                    
                    
                        | 7 | Walk | 
                                    
                    
                        | 8 | Other (specify) | 
                                    
                    
                        | 9 |  | 
                                    
                    
                        | 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.