| Value | Category | Cases | |
|---|---|---|---|
| 1980 | 1 | 
                                    
                                    0%
                                 | |
| 1983 | 4 | 
                                    
                                    0%
                                 | |
| 1984 | 3 | 
                                    
                                    0%
                                 | |
| 1985 | 8 | 
                                    
                                    0.1%
                                 | |
| 1986 | 14 | 
                                    
                                    0.2%
                                 | |
| 1987 | 16 | 
                                    
                                    0.2%
                                 | |
| 1988 | 19 | 
                                    
                                    0.2%
                                 | |
| 1989 | 24 | 
                                    
                                    0.3%
                                 | |
| 1990 | 61 | 
                                    
                                    0.7%
                                 | |
| 1991 | 26 | 
                                    
                                    0.3%
                                 | |
| 1992 | 50 | 
                                    
                                    0.6%
                                 | |
| 1993 | 61 | 
                                    
                                    0.7%
                                 | |
| 1994 | 78 | 
                                    
                                    0.9%
                                 | |
| 1995 | 107 | 
                                    
                                    1.2%
                                 | |
| 1996 | 114 | 
                                    
                                    1.3%
                                 | |
| 1997 | 119 | 
                                    
                                    1.3%
                                 | |
| 1998 | 195 | 
                                    
                                    2.2%
                                 | |
| 1999 | 149 | 
                                    
                                    1.7%
                                 | |
| 2000 | 213 | 
                                    
                                    2.4%
                                 | |
| 2001 | 124 | 
                                    
                                    1.4%
                                 | |
| 2002 | 157 | 
                                    
                                    1.7%
                                 | |
| 2003 | 142 | 
                                    
                                    1.6%
                                 | |
| 2004 | 141 | 
                                    
                                    1.6%
                                 | |
| 2005 | 142 | 
                                    
                                    1.6%
                                 | |
| 2006 | 146 | 
                                    
                                    1.6%
                                 | |
| 2007 | 140 | 
                                    
                                    1.6%
                                 | |
| 2008 | 217 | 
                                    
                                    2.4%
                                 | |
| 2009 | 149 | 
                                    
                                    1.7%
                                 | |
| 2010 | 209 | 
                                    
                                    2.3%
                                 | |
| 2011 | 185 | 
                                    
                                    2.1%
                                 | |
| 2012 | 219 | 
                                    
                                    2.4%
                                 | |
| 2013 | 233 | 
                                    
                                    2.6%
                                 | |
| 2014 | 240 | 
                                    
                                    2.7%
                                 | |
| 2015 | 246 | 
                                    
                                    2.7%
                                 | |
| 2016 | 244 | 
                                    
                                    2.7%
                                 | |
| 2017 | 254 | 
                                    
                                    2.8%
                                 | |
| 2018 | 141 | 
                                    
                                    1.6%
                                 | |
| 9997 | INCOHERENT | 6 | 
                                    
                                    0.1%
                                 | 
| 9998 | NSP | 202 | 
                                    
                                    2.2%
                                 | 
| Sysmiss | 4181 | 
                                    
                                    46.6%
                                 |