Year	Number
1960	9300
1961	9300
1962	9300
1963	9300
1964	9300
1965	12542
1966	12542
1967	12542
1968	12542
1969	12542
1970	16034
1971	16034
1972	16034
1973	16034
1974	16034
1975	17500
1976	17900
1977	19383
1978	20500
1979	21500
1980	22371
1981	23499
1982	26453
1983	27480
1984	28720
1985	29823
1986	31356
1987	32818
1988	34588
1989	36298
1990	37319
1991	38989
1992	39786
1993	42068
1994	44215
1995	46402
1996	48524
1997	51853
1998	53730
1999	54933
2000	56073
2001	56151
2002	56000
2003	54000
2004	53850
2005	52471
2006	57654
2007	57600
2008	57600
2009	57700
2010	57800
2012	69000
2013	72000
2014	29234
2015	12000
2016	20351
2017	21883
2019	25000
2020	25000
2021	25000