Year	Number
1970	2457903
1971	2535012
1972	2562447
1973	2674460
1974	2823126
1975	2947402
1976	3145257
1977	3425864
1978	3635924
1979	3793659
1980	3924999
1981	3871592
1982	4134705
1983	4343092
1984	4508280
1985	4803246
1986	5068252
1987	5447390
1988	5581956
1989	5502300
1990	5464727
1991	5455817
1992	5498636
1993	5868562
1994	6209519
1995	6309333
1996	6379087
1997	6702222
1998	6868025
1999	6943603
2000	7617947
2001	7786902
2002	8094729
2003	8511864
2004	8938360
2005	9042629
2006	9215122
2007	9386506
2008	9836286
2009	10300000
2010	11000000
2011	12000000
2012	12800000
2013	13100000
2014	13100000
2015	13300000
2016	13500000
2017	15100000
2018	15500000