Year	Number
1970	104000000
1971	114000000
1972	123000000
1973	131000000
1974	134000000
1975	140000000
1976	151000000
1977	168000000
1978	181000000
1979	192000000
1980	190000000
1981	191000000
1982	189000000
1983	193000000
1984	197000000
1985	195000000
1986	212000000
1987	219000000
1988	224000000
1989	226000000
1990	231000000
1991	239000000
1992	248000000
1993	258000000
1994	265000000
1995	275000000
1996	286000000
1997	298000000
1998	308000000
1999	317000000
2000	331000000
2001	342000000
2002	356000000
2003	368000000
2004	377000000
2005	383000000
2006	387000000
2007	393000000
2008	399000000
2009	401000000
2010	410000000
2011	419000000
2012	425000000
2013	432000000
2014	441000000
2015	445000000
2016	449000000
2017	450000000
2018	456000000