| Value | Category | 
                                    
                    
                        | 1 | Yes, still a member | 
                                    
                    
                        | 2 | No, no longer a member' | 
                                    
                    
                        | 3 | Still a member but 6 years or older | 
                                    
                    
                        | 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.