| Value | Category | 
                                    
                    
                        | 20072 |  | 
                                    
                    
                        | 20081 | First quarter 2008 | 
                                    
                    
                        | 20082 | Second quarter 2008 | 
                                    
                    
                        | 20083 | Third quarter 2008 | 
                                    
                    
                        | 20084 | Fourth quarter 2008 | 
                            
            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.