Year	Number
1970	60500000
1971	65200000
1972	66800000
1973	68300000
1974	70000000
1975	71200000
1976	72000000
1977	73100000
1978	73600000
1979	72200000
1980	75100000
1981	74600000
1982	74800000
1983	74400000
1984	74500000
1985	73900000
1986	74000000
1987	73700000
1988	72700000
1989	71800000
1990	70700000
1991	70400000
1992	70500000
1993	71500000
1994	72300000
1995	72400000
1996	72300000
1997	69700000
1998	74200000
1999	74000000
2000	75000000
2001	75300000
2002	75200000
2003	75700000
2004	73500000
2005	73400000
2006	73600000
2007	73200000
2008	73100000
2009	72600000
2010	72100000
2011	71400000
2012	71100000
2013	71400000
2014	71300000
2015	71000000
2016	70800000
2017	70600000
2018	69900000