Year	Number
1970	3127211
1971	3244079
1972	3487954
1973	3712868
1974	3924302
1975	4290267
1976	4639548
1977	4983997
1978	5538778
1979	6175220
1980	6930874
1981	7700700
1982	8285818
1983	8961521
1984	9784025
1985	10300000
1986	9966545
1987	10200000
1988	10300000
1989	10200000
1990	10600000
1991	11000000
1992	11400000
1993	11800000
1994	12300000
1995	12900000
1996	13300000
1997	13600000
1998	14300000
1999	14900000
2000	15900000
2001	17300000
2002	18600000
2003	20300000
2004	22400000
2005	23700000
2006	25300000
2007	26400000
2008	29500000
2009	32400000
2010	35400000
2011	37600000
2012	40000000
2013	44300000
2014	44100000
2015	46400000
2016	47100000
2017	48800000
2018	50600000