| Value | Category | Cases | |
|---|---|---|---|
| 1960 | 1 | 
                                    
                                    0.5%
                                 | |
| 1964 | 1 | 
                                    
                                    0.5%
                                 | |
| 1977 | 1 | 
                                    
                                    0.5%
                                 | |
| 1978 | 1 | 
                                    
                                    0.5%
                                 | |
| 1980 | 1 | 
                                    
                                    0.5%
                                 | |
| 1982 | 2 | 
                                    
                                    1%
                                 | |
| 1983 | 1 | 
                                    
                                    0.5%
                                 | |
| 1985 | 4 | 
                                    
                                    2.1%
                                 | |
| 1986 | 2 | 
                                    
                                    1%
                                 | |
| 1987 | 1 | 
                                    
                                    0.5%
                                 | |
| 1988 | 3 | 
                                    
                                    1.6%
                                 | |
| 1989 | 7 | 
                                    
                                    3.7%
                                 | |
| 1990 | 16 | 
                                    
                                    8.4%
                                 | |
| 1991 | 3 | 
                                    
                                    1.6%
                                 | |
| 1992 | 18 | 
                                    
                                    9.4%
                                 | |
| 1993 | 16 | 
                                    
                                    8.4%
                                 | |
| 1994 | 8 | 
                                    
                                    4.2%
                                 | |
| 1995 | 13 | 
                                    
                                    6.8%
                                 | |
| 1996 | 2 | 
                                    
                                    1%
                                 | |
| 1997 | 11 | 
                                    
                                    5.8%
                                 | |
| 1998 | 8 | 
                                    
                                    4.2%
                                 | |
| 1999 | 1 | 
                                    
                                    0.5%
                                 | |
| 2000 | 27 | 
                                    
                                    14.1%
                                 | |
| 2001 | 4 | 
                                    
                                    2.1%
                                 | |
| 2002 | 6 | 
                                    
                                    3.1%
                                 | |
| 2003 | 17 | 
                                    
                                    8.9%
                                 | |
| 2004 | 2 | 
                                    
                                    1%
                                 | |
| 2005 | 10 | 
                                    
                                    5.2%
                                 | |
| 2006 | 3 | 
                                    
                                    1.6%
                                 | |
| 2007 | 1 | 
                                    
                                    0.5%
                                 | |
| Sysmiss | 5143 |