| Value | Category | Cases | |
|---|---|---|---|
| 1984 | 1 | 
                                    
                                    10%
                                 | |
| 1997 | 1 | 
                                    
                                    10%
                                 | |
| 1998 | 2 | 
                                    
                                    20%
                                 | |
| 2001 | 3 | 
                                    
                                    30%
                                 | |
| 2002 | 3 | 
                                    
                                    30%
                                 | |
| Sysmiss | 1838 |