Year	Number
1970	65718456
1971	67304712
1972	65830736
1973	63204128
1974	64642356
1975	63490752
1976	62774224
1977	61148928
1978	63800168
1979	64182956
1980	62989540
1981	61205632
1982	59461640
1983	58539688
1984	58010752
1985	58657324
1986	57983888
1987	59964312
1988	58262192
1989	55544536
1990	58236256
1991	57631864
1992	57919904
1993	57348280
1994	56085428
1995	57412312
1996	56260988
1997	57241668
1998	56974548
1999	55222156
2000	51137416
2001	49266528
2002	48216924
2003	41884064
2004	37299848
2005	33018782
2006	30962432
2007	25380416
2008	24737434
2009	25322450
2010	24300000
2011	24600000
2012	22900000
2013	21000000
2014	20500000
2015	21000000
2016	20300000
2017	19900000
2018	19700000