| Value | Category | 
                                    
                    
                        | -9 | Don't know (spontaneous) | 
                                    
                    
                        | 1 |  | 
                                    
                    
                        | 5 |  | 
                                    
                    
                        | 7 |  | 
                                    
                    
                        | 10 |  | 
                                    
                    
                        | 15 |  | 
                                    
                    
                        | 20 |  | 
                                    
                    
                        | 30 |  | 
                                    
                    
                        | 33 |  | 
                                    
                    
                        | 35 |  | 
                                    
                    
                        | 40 |  | 
                                    
                    
                        | 45 |  | 
                                    
                    
                        | 50 |  | 
                                    
                    
                        | 55 |  | 
                                    
                    
                        | 60 |  | 
                                    
                    
                        | 65 |  | 
                                    
                    
                        | 66 |  | 
                                    
                    
                        | 70 |  | 
                                    
                    
                        | 75 |  | 
                                    
                    
                        | 77 |  | 
                                    
                    
                        | 78 |  | 
                                    
                    
                        | 80 |  | 
                                    
                    
                        | 84 |  | 
                                    
                    
                        | 85 |  | 
                                    
                    
                        | 88 |  | 
                                    
                    
                        | 89 |  | 
                                    
                    
                        | 90 |  | 
                                    
                    
                        | 92 |  | 
                                    
                    
                        | 93 |  | 
                                    
                    
                        | 95 |  | 
                                    
                    
                        | 96 |  | 
                                    
                    
                        | 97 |  | 
                                    
                    
                        | 98 |  | 
                                    
                    
                        | 99 |  | 
                                    
                    
                        | 100 |  | 
                            
            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.