Year	Number
1970	62182140
1971	64705352
1972	63912836
1973	58879188
1974	58035568
1975	55920520
1976	55952624
1977	58694424
1978	64796520
1979	65304808
1980	63721496
1981	61244728
1982	59927576
1983	59051108
1984	57498296
1985	54280988
1986	50829416
1987	49338056
1988	47344136
1989	45030432
1990	45739792
1991	45277236
1992	45633700
1993	45015020
1994	45074608
1995	47262244
1996	48085288
1997	48590192
1998	46144872
1999	41604560
2000	38569652
2001	36701000
2002	35653840
2003	28784808
2004	26779314
2005	24663806
2006	24669978
2007	21341244
2008	20458632
2009	20343080
2010	20200000
2011	19800000
2012	19600000
2013	19200000
2014	19400000
2015	20100000
2016	20000000
2017	20000000
2018	20100000