Year	Number
1973	14768790
1974	14735343
1975	14634651
1976	14638149
1977	14217610
1978	13676886
1979	12938990
1980	12774768
1981	12661417
1982	12869649
1983	13063584
1984	13499313
1985	14265121
1986	15170425
1987	16172721
1988	16822384
1989	17802932
1990	18328552
1991	18376880
1992	19162728
1993	19393200
1994	19861364
1995	20388840
1996	21813984
1997	21054848
1998	21252600
1999	21218412
2000	20937474
2001	20412924
2002	19598060
2003	18224360
2004	17678292
2005	17566036
2006	17014002
2007	16969748
2008	16780956
2009	16837276
2010	17600000
2011	17300000
2012	17200000
2013	17600000
2014	17500000
2015	18100000
2016	18400000
2017	19000000
2018	19300000