Year	Number
1970	7251637
1971	6925730
1972	7367816
1973	7817231
1974	8204638
1975	8626106
1976	9449700
1977	9984726
1978	10200000
1979	12200000
1980	12800000
1981	13500000
1982	13900000
1983	14500000
1984	16100000
1985	15000000
1986	18400000
1987	19000000
1988	19400000
1989	19600000
1990	19700000
1991	19600000
1992	19500000
1993	19500000
1994	19900000
1995	20900000
1996	22000000
1997	22400000
1998	23700000
1999	23200000
2000	22700000
2001	22800000
2002	22200000
2003	22100000
2004	24000000
2005	24800000
2006	26900000
2007	28900000
2008	30900000
2009	31900000
2010	32900000
2011	33000000
2012	32700000
2013	35500000
2014	34000000
2015	32400000
2016	31600000
2017	30900000
2018	30800000