Year	Number
1970	99500000
1971	108000000
1972	117000000
1973	125000000
1974	128000000
1975	134000000
1976	145000000
1977	162000000
1978	175000000
1979	186000000
1980	184000000
1981	184000000
1982	182000000
1983	185000000
1984	189000000
1985	187000000
1986	204000000
1987	210000000
1988	215000000
1989	217000000
1990	221000000
1991	229000000
1992	238000000
1993	247000000
1994	254000000
1995	264000000
1996	275000000
1997	286000000
1998	295000000
1999	303000000
2000	316000000
2001	326000000
2002	338000000
2003	349000000
2004	356000000
2005	360000000
2006	363000000
2007	368000000
2008	371000000
2009	373000000
2010	380000000
2011	386000000
2012	391000000
2013	397000000
2014	406000000
2015	409000000
2016	412000000
2017	412000000
2018	418000000