| Value | Category | 
                                    
                    
                        | -9 | No answer | 
                                    
                    
                        | -7 | Not sure | 
                                    
                    
                        | 0 |  | 
                                    
                    
                        | 150 |  | 
                                    
                    
                        | 675 |  | 
                                    
                    
                        | 1000 |  | 
                                    
                    
                        | 1500 |  | 
                                    
                    
                        | 2000 |  | 
                                    
                    
                        | 3000 |  | 
                                    
                    
                        | 3500 |  | 
                                    
                    
                        | 4200 |  | 
                                    
                    
                        | 5000 |  | 
                                    
                    
                        | 5940 |  | 
                                    
                    
                        | 10000 |  | 
                                    
                    
                        | 30000 |  | 
                            
            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.