Year	Number
1960	156
1961	148
1962	139
1963	129
1964	118
1965	106
1966	94
1967	83
1968	72
1969	63
1970	56
1971	50
1972	45
1973	41
1974	37
1975	33
1976	31
1977	30
1978	28
1979	26
1980	24
1981	22
1982	20
1983	19
1984	18
1985	18
1986	18
1987	17
1988	17
1989	18
1990	18
1991	18
1992	18
1993	18
1994	19
1995	20
1996	21
1997	22
1998	21
1999	20
2000	21
2001	21
2002	19
2003	18
2004	18
2005	17
2006	16
2007	16
2008	17
2009	17
2010	16
2011	15
2012	14
2013	13
2014	12
2015	12
2016	12
2017	11
2018	11
2019	11
2020	11
2021	11
2022	11