Year	Number
1960	6047
1961	6047
1962	6047
1963	6047
1964	6047
1965	9200
1966	9200
1967	9200
1968	9200
1969	9200
1970	11211
1971	11211
1972	11211
1973	11211
1974	11211
1975	15434
1976	15500
1977	16814
1978	19943
1979	22456
1980	23627
1981	24890
1982	29232
1983	31575
1984	35346
1985	39589
1986	41828
1987	47355
1988	49883
1989	52595
1990	55554
1991	64022
1992	79422
1993	106926
1994	129443
1995	148185
1996	183861
1997	222747
1998	245367
1999	257099
2000	280885
2001	306773
2002	317792
2003	348202
2004	353808
2005	357490
2006	357340
2007	360762
2008	363600
2009	375160
2010	387700
2011	374600
2012	349100
2013	363000
2014	372200
2015	380000
2016	389500
2017	413100
2018	434300
2019	458700
2020	478700
2021	469100
2022	462100