Year	Number
1970	92100000
1971	101000000
1972	109000000
1973	117000000
1974	119000000
1975	124000000
1976	135000000
1977	152000000
1978	164000000
1979	174000000
1980	171000000
1981	171000000
1982	168000000
1983	170000000
1984	173000000
1985	170000000
1986	186000000
1987	192000000
1988	196000000
1989	198000000
1990	202000000
1991	209000000
1992	216000000
1993	224000000
1994	230000000
1995	238000000
1996	248000000
1997	258000000
1998	266000000
1999	273000000
2000	285000000
2001	293000000
2002	304000000
2003	313000000
2004	319000000
2005	322000000
2006	323000000
2007	326000000
2008	328000000
2009	327000000
2010	331000000
2011	336000000
2012	339000000
2013	341000000
2014	349000000
2015	350000000
2016	351000000
2017	351000000
2018	354000000