| Value | Category | Cases | |
|---|---|---|---|
| 1990 | 1 | 
                                                                 
                                    
                                    6.7%
                                 
                                                             | 
                                                        
                    |
| 2000 | 2 | 
                                                                 
                                    
                                    13.3%
                                 
                                                             | 
                                                        
                    |
| 2001 | 6 | 
                                                                 
                                    
                                    40%
                                 
                                                             | 
                                                        
                    |
| 2003 | 4 | 
                                                                 
                                    
                                    26.7%
                                 
                                                             | 
                                                        
                    |
| 2004 | 2 | 
                                                                 
                                    
                                    13.3%
                                 
                                                             |