Year	Number
1971	4006527
1972	4133008
1973	4268445
1974	4675716
1975	4815483
1976	4945770
1977	5055642
1978	5110453
1979	5134876
1980	5116354
1981	5087036
1982	5040235
1983	4977000
1984	4864000
1985	4623000
1986	4474000
1987	4270000
1988	4086000
1989	3936237
1990	3833000
1991	3855200
1992	3883500
1993	4017626
1994	3996849
1995	4062286
1996	4077942
1997	4113465
1998	4342524
1999	4193904
2000	4255837
2001	4322915
2002	4374779
2003	4474812
2004	4401785
2005	4414562
2006	4381851
2007	4317382
2008	4639448
2009	4749753
2010	4805310
2011	4549325
2012	4378872
2013	4413924
2014	4471247.27375
2015	4492280.10636
2016	4151173
2017	4174850