Year	Number
1970	44163836
1971	44971880
1972	44427960
1973	42224520
1974	42025624
1975	41437248
1976	41033736
1977	40896552
1978	42591736
1979	42058376
1980	41064960
1981	39824512
1982	39557712
1983	39249928
1984	39289544
1985	38844616
1986	38382500
1987	38669984
1988	37781116
1989	37082128
1990	38772016
1991	38653672
1992	39792296
1993	40760872
1994	41950864
1995	43840068
1996	45987324
1997	46871328
1998	45538164
1999	43242008
2000	40948784
2001	39469740
2002	38157092
2003	36025544
2004	33657160
2005	31243090
2006	31150806
2007	26870754
2008	27008540
2009	28097332
2010	28900000
2011	29200000
2012	27800000
2013	27100000
2014	26400000
2015	26800000
2016	26300000
2017	26300000
2018	26100000