| Value | Category | 
                                    
                    
                        | -4 | Missing data | 
                                    
                    
                        | -3 | Refused to answer | 
                                    
                    
                        | -2 | Not applicable | 
                                    
                    
                        | -1 | Don't know | 
                                    
                    
                        | 1 | Yes | 
                                    
                    
                        | 2 | No | 
                            
            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.