Year	Number
1970	58200000
1971	63000000
1972	64700000
1973	66800000
1974	68800000
1975	70300000
1976	71500000
1977	72900000
1978	73700000
1979	72700000
1980	76100000
1981	76000000
1982	76900000
1983	77000000
1984	77600000
1985	77500000
1986	78100000
1987	78100000
1988	77500000
1989	76800000
1990	75800000
1991	75800000
1992	76200000
1993	77500000
1994	78800000
1995	79000000
1996	79000000
1997	76500000
1998	81900000
1999	82400000
2000	84000000
2001	85300000
2002	86200000
2003	87500000
2004	85500000
2005	86200000
2006	86900000
2007	86900000
2008	86800000
2009	86800000
2010	86600000
2011	86400000
2012	86100000
2013	88100000
2014	88600000
2015	88700000
2016	88800000
2017	89400000
2018	88700000