| Value | Category | Cases | |
|---|---|---|---|
| 1960 | 1 | 
                                    
                                    0.3%
                                 | |
| 1965 | 2 | 
                                    
                                    0.6%
                                 | |
| 1966 | 2 | 
                                    
                                    0.6%
                                 | |
| 1970 | 1 | 
                                    
                                    0.3%
                                 | |
| 1975 | 2 | 
                                    
                                    0.6%
                                 | |
| 1976 | 3 | 
                                    
                                    0.9%
                                 | |
| 1978 | 6 | 
                                    
                                    1.9%
                                 | |
| 1979 | 3 | 
                                    
                                    0.9%
                                 | |
| 1980 | 7 | 
                                    
                                    2.2%
                                 | |
| 1981 | 2 | 
                                    
                                    0.6%
                                 | |
| 1982 | 2 | 
                                    
                                    0.6%
                                 | |
| 1983 | 2 | 
                                    
                                    0.6%
                                 | |
| 1984 | 1 | 
                                    
                                    0.3%
                                 | |
| 1985 | 5 | 
                                    
                                    1.6%
                                 | |
| 1986 | 1 | 
                                    
                                    0.3%
                                 | |
| 1987 | 1 | 
                                    
                                    0.3%
                                 | |
| 1990 | 4 | 
                                    
                                    1.3%
                                 | |
| 1991 | 1 | 
                                    
                                    0.3%
                                 | |
| 1992 | 2 | 
                                    
                                    0.6%
                                 | |
| 1993 | 2 | 
                                    
                                    0.6%
                                 | |
| 1994 | 2 | 
                                    
                                    0.6%
                                 | |
| 1995 | 2 | 
                                    
                                    0.6%
                                 | |
| 1996 | 2 | 
                                    
                                    0.6%
                                 | |
| 1997 | 2 | 
                                    
                                    0.6%
                                 | |
| 1999 | 1 | 
                                    
                                    0.3%
                                 | |
| 2000 | 13 | 
                                    
                                    4.1%
                                 | |
| 2001 | 4 | 
                                    
                                    1.3%
                                 | |
| 2002 | 7 | 
                                    
                                    2.2%
                                 | |
| 2003 | 8 | 
                                    
                                    2.5%
                                 | |
| 2004 | 2 | 
                                    
                                    0.6%
                                 | |
| 2005 | 6 | 
                                    
                                    1.9%
                                 | |
| 2006 | 14 | 
                                    
                                    4.4%
                                 | |
| 2007 | 10 | 
                                    
                                    3.2%
                                 | |
| 2008 | 8 | 
                                    
                                    2.5%
                                 | |
| 2009 | 6 | 
                                    
                                    1.9%
                                 | |
| 2010 | 23 | 
                                    
                                    7.3%
                                 | |
| 2011 | 5 | 
                                    
                                    1.6%
                                 | |
| 2012 | 8 | 
                                    
                                    2.5%
                                 | |
| 2013 | 18 | 
                                    
                                    5.7%
                                 | |
| 2014 | 10 | 
                                    
                                    3.2%
                                 | |
| 2015 | 20 | 
                                    
                                    6.3%
                                 | |
| 2016 | 8 | 
                                    
                                    2.5%
                                 | |
| 2017 | 12 | 
                                    
                                    3.8%
                                 | |
| 2018 | 16 | 
                                    
                                    5%
                                 | |
| 2019 | 15 | 
                                    
                                    4.7%
                                 | |
| 2020 | 17 | 
                                    
                                    5.4%
                                 | |
| 2021 | 9 | 
                                    
                                    2.8%
                                 | |
| 2022 | 14 | 
                                    
                                    4.4%
                                 | |
| 2023 | 5 | 
                                    
                                    1.6%
                                 |