| Value | Category | 
                                    
                    
                        | -99 | Refused to respond | 
                                    
                    
                        | -98 | Don't know | 
                                    
                    
                        | 1 | Yes, often | 
                                    
                    
                        | 2 | Yes, but not often | 
                                    
                    
                        | 3 | No | 
                                    
                    
                        | 11 | .Z | 
                                    
                    
                        | 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.