| Value | Category | 
                                    
                    
                        | 0 |  | 
                                    
                    
                        | 1 | last 2 weeks | 
                                    
                    
                        | 2 | 2-4 weeks ago | 
                                    
                    
                        | 3 | 1-6 months ago | 
                                    
                    
                        | 4 | 7-12 months ago | 
                                    
                    
                        | 5 | more than one year ago | 
                            
            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.