Year	Number
1980	3
1981	7
1982	2
1983	3
1984	6
1985	1
1986	1
1987	2
1988	5
1989	1
1990	4
1991	1
1992	2
1994	3
1999	4
2012	30
2014	7
2015	1
2016	3
2017	2
2018	1
2021	2