| Value | Category | 
                                    
                    
                        | 2014 |  | 
                                    
                    
                        | 2015 |  | 
                                    
                    
                        | 3333 | Missing | 
                                    
                    
                        | 5555 | Not Applicable | 
                                    
                    
                        | 8888 | Refused | 
                                    
                    
                        | 9999 | Don't Know | 
                                    
                    
                        | 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.