| Value | Category | 
                                    
                    
                        | -9 | don't know | 
                                    
                    
                        | -8 | refusal | 
                                    
                    
                        | 2 |  | 
                                    
                    
                        | 3 |  | 
                                    
                    
                        | 5 |  | 
                                    
                    
                        | 6 |  | 
                                    
                    
                        | 7 |  | 
                                    
                    
                        | 8 |  | 
                                    
                    
                        | 9 |  | 
                                    
                    
                        | 10 |  | 
                                    
                    
                        | 15 |  | 
                                    
                    
                        | 16 |  | 
                                    
                    
                        | 18 |  | 
                                    
                    
                        | 20 |  | 
                                    
                    
                        | 25 |  | 
                                    
                    
                        | 30 |  | 
                                    
                    
                        | 35 |  | 
                                    
                    
                        | 40 |  | 
                                    
                    
                        | 48 |  | 
                                    
                    
                        | 50 |  | 
                                    
                    
                        | 60 |  | 
                                    
                    
                        | 90 |  | 
                                    
                    
                        | 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.