Year	Number of
1980	1
1981	0
1982	2
1983	3
1984	1
1985	0
1986	5
1987	0
1988	3
1990	0
1992	2
1993	1
1994	2
1995	0
1996	2
1997	0
1998	0
1999	1
2000	0
2001	0
2002	4
2003	0
2004	0
2005	0
2006	0
2007	0
2008	0
2009	0
2010	0
2011	1
2012	0
2013	0
2014	0
2015	0
2017	0
2018	2
2019	0
2020	1