Year	Number
1970	17000
1971	17000
1972	17000
1973	17000
1974	17000
1975	21947
1976	25393
1977	28421
1978	30349
1979	29317
1980	30827
1981	32998
1982	35946
1983	39548
1984	41853
1985	43364
1986	44118
1987	45921
1988	45483
1989	46169
1990	46328
1991	48305
1992	54280
1993	66810
1994	85254
1995	96611
1996	111397
1997	122817
1998	141233
1999	150258
2000	164484
2001	157753
2002	171632
2003	205004
2004	214480
2005	220869
2006	247862
2007	249000
2008	254438
2009	254686
2010	258325
2011	287618
2012	299123
2013	324971
2014	339629
2015	354017
2016	366636
2017	375856
2018	325821
2019	228782
2020	224124
2021	207577
2022	215729