| Value | Category | 
                                    
                    
                        | 1 | a lot worse | 
                                    
                    
                        | 2 | worse | 
                                    
                    
                        | 3 | no effect | 
                                    
                    
                        | 4 | better | 
                                    
                    
                        | 5 | a lot better | 
                                    
                    
                        | 6 | don't know | 
                                    
                    
                        | 97 | n/a | 
                                    
                    
                        | 98 | refused | 
                                    
                    
                        | 99 | missing data | 
                            
            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.