Year	Number of
1980	78
1981	11
1982	14
1983	4
1984	23
1985	14
1986	9
1987	3
1988	6
1989	3
1990	2
1991	1
1992	4
1993	13
1994	0
1995	13
1996	6
1997	6
1998	8
1999	9
2000	16
2001	10
2002	10
2003	14
2004	8
2005	7
2006	13
2007	12
2008	12
2009	9
2010	15
2011	17
2012	30
2013	3
2014	5
2015	7
2016	6
2017	2
2018	6
2019	4
2020	13