Year	Number
1981	2
1985	4
1988	3
1990	1
1991	2
1993	2
1994	5
1995	3
1996	3
1997	3
1998	3
2008	2
2011	1
2012	4
2013	2
2014	3
2015	1
2016	2
2017	1
2018	16
2019	4
2020	6
2021	6