Year	Number of
1980	0
1981	1
1982	0
1983	0
1984	0
1985	2
1986	0
1987	9
1988	1
1989	0
1990	1
1991	1
1992	1
1994	0
1995	2
1996	0
1999	0
2000	0
2001	0
2003	0
2005	0
2006	0
2007	0
2008	0
2009	0
2010	0
2011	0
2012	0
2013	0
2014	0
2015	2
2016	0
2017	0
2020	0