| Value | Category | 
                                    
                    
                        | 1 | overall, great quality | 
                                    
                    
                        | 2 | overall, fair quality | 
                                    
                    
                        | 3 | overall, poor quality | 
                                    
                    
                        | 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.