Year	Number
1960	7700
1961	7700
1962	7700
1963	7700
1964	7700
1965	9300
1966	9300
1967	9300
1968	9300
1969	9300
1970	16000
1971	16000
1972	16000
1973	16000
1974	16000
1975	21500
1976	22200
1977	22200
1978	25300
1979	25300
1980	25800
1981	31700
1982	28000
1983	29000
1984	30000
1985	31000
1986	32000
1987	33000
1988	34000
1989	35000
1990	36200
1991	37000
1992	29000
1993	29000
1994	29000
1995	29000
1996	29000
1997	29000
1998	29000
1999	29000
2000	29000
2001	29000
2002	33050
2003	36700
2009	5130
2010	16620
2011	13509
2012	90017
2013	95769
2014	101931
2015	110000
2016	114192
2017	118769
2018	127794
2019	134636
2020	145787
2021	145787