| Value | Category | 
                                    
                    
                        | 1 | are taken directly from business records | 
                                    
                    
                        | 2 | are estimates computed with some precision | 
                                    
                    
                        | 3 | are arbitrary and unreliable numbers | 
                            
            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.