Year	Number
1970	21471
1971	22864
1972	24032
1973	25394
1974	26339
1975	28681
1976	29765
1977	32554
1978	34213
1979	36442
1980	38422
1981	40489
1982	44426
1983	49206
1984	57078
1985	61424
1986	73141
1987	72970
1988	75561
1989	81418
1990	84149
1991	78259
1992	86821
1993	91905
1994	84043
1995	82745
1996	81564
1997	89247
1998	99237
1999	109733
2000	110366
2001	127038
2002	139484
2003	145703
2004	147291
2005	139641
2006	150135
2007	152086
2008	159516
2009	168376
2010	172403
2011	169503
2012	170652
2013	185548
2014	191217
2015	192566
2016	202617
2017	207238