Year	Number
1970	73518032
1971	76224632
1972	75664928
1973	70680216
1974	69985936
1975	67757760
1976	67689128
1977	70289608
1978	76377624
1979	76932528
1980	75208352
1981	72664008
1982	71860304
1983	71094560
1984	69881184
1985	67056864
1986	63876168
1987	63054080
1988	61365232
1989	59640100
1990	61075360
1991	60669744
1992	61813072
1993	61791384
1994	62069420
1995	64409888
1996	65683968
1997	66059716
1998	63627772
1999	59363588
2000	56020952
2001	53722520
2002	51562916
2003	43815148
2004	41013144
2005	38195640
2006	37202272
2007	33333576
2008	31462564
2009	31200656
2010	31400000
2011	30600000
2012	30100000
2013	29700000
2014	29700000
2015	30900000
2016	31000000
2017	31300000
2018	31800000