| Value | 
                    Category | 
                                                                            
                                    
                    
                        | -9 | 
                        Don't know (SPONTANEOUS)  | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 7 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 20 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 40 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 48 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 50 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 55 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 60 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 62 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 65 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 70 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 75 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 80 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 85 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 90 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 95 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 97 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 98 | 
                          | 
                        
                            
                        
                        
                        
                        
                            
                    
                                    
                    
                        | 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.