Year	Number
1970	3864403
1971	3955139
1972	4153092
1973	4395691
1974	4584751
1975	4898500
1976	5188763
1977	5426975
1978	5804566
1979	6293558
1980	6625164
1981	7059177
1982	7272178
1983	7490281
1984	7747367
1985	7962547
1986	8215529
1987	8388344
1988	8560197
1989	8775617
1990	8582392
1991	9008254
1992	9235744
1993	9507302
1994	10000000
1995	10700000
1996	11100000
1997	11500000
1998	12000000
1999	12500000
2000	13300000
2001	13900000
2002	14600000
2003	16200000
2004	17600000
2005	18500000
2006	19600000
2007	20300000
2008	21700000
2009	23000000
2010	24000000
2011	25000000
2012	26100000
2013	26300000
2014	26700000
2015	27800000
2016	28600000
2017	29700000
2018	30300000