Year	Number
1970	5858187
1971	5976109
1972	6156970
1973	6435510
1974	6550311
1975	6803355
1976	7015818
1977	7286088
1978	7682107
1979	8199179
1980	8925270
1981	8963437
1982	9446389
1983	10100000
1984	10600000
1985	10800000
1986	11000000
1987	11400000
1988	11700000
1989	12100000
1990	12200000
1991	13200000
1992	14100000
1993	15100000
1994	16300000
1995	17800000
1996	19100000
1997	20100000
1998	22100000
1999	23500000
2000	25000000
2001	26700000
2002	28500000
2003	29700000
2004	30900000
2005	32300000
2006	34300000
2007	35800000
2008	37700000
2009	40400000
2010	43000000
2011	45300000
2012	48000000
2013	51200000
2014	53500000
2015	55500000
2016	58400000
2017	59500000
2018	61100000