| Value | Category | 
                                    
                    
                        | 1 | Jan | 
                                    
                    
                        | 2 | Feb | 
                                    
                    
                        | 3 | March | 
                                    
                    
                        | 4 | April | 
                                    
                    
                        | 5 | May | 
                                    
                    
                        | 6 | June | 
                                    
                    
                        | 7 | July | 
                                    
                    
                        | 8 | Aug | 
                                    
                    
                        | 9 | Sept | 
                                    
                    
                        | 10 | Oct | 
                                    
                    
                        | 11 | Nov | 
                                    
                    
                        | 12 | Dec | 
                                    
                    
                        | Sysmiss |  | 
                            
            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.