| Value | Category | 
                                    
                    
                        | -9 | Don't know (SPONTANEOUS) | 
                                    
                    
                        | 1 |  | 
                                    
                    
                        | 5 |  | 
                                    
                    
                        | 6 |  | 
                                    
                    
                        | 7 |  | 
                                    
                    
                        | 10 |  | 
                                    
                    
                        | 15 |  | 
                                    
                    
                        | 20 |  | 
                                    
                    
                        | 25 |  | 
                                    
                    
                        | 27 |  | 
                                    
                    
                        | 30 |  | 
                                    
                    
                        | 33 |  | 
                                    
                    
                        | 35 |  | 
                                    
                    
                        | 38 |  | 
                                    
                    
                        | 40 |  | 
                                    
                    
                        | 49 |  | 
                                    
                    
                        | 50 |  | 
                                    
                    
                        | 51 |  | 
                                    
                    
                        | 55 |  | 
                                    
                    
                        | 56 |  | 
                                    
                    
                        | 60 |  | 
                                    
                    
                        | 75 |  | 
                                    
                    
                        | 80 |  | 
                                    
                    
                        | 100 |  | 
                                    
                    
                        | 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.