Year	Number
1970	29700000
1971	36500000
1972	41900000
1973	47000000
1974	46200000
1975	48900000
1976	58000000
1977	72500000
1978	82900000
1979	82000000
1980	76600000
1981	73600000
1982	67900000
1983	65900000
1984	65000000
1985	67700000
1986	70100000
1987	73300000
1988	74300000
1989	72800000
1990	69900000
1991	70600000
1992	72300000
1993	74100000
1994	75100000
1995	79400000
1996	85200000
1997	90700000
1998	95300000
1999	99700000
2000	105000000
2001	110000000
2002	116000000
2003	123000000
2004	127000000
2005	127000000
2006	127000000
2007	128000000
2008	125000000
2009	124000000
2010	122000000
2011	121000000
2012	120000000
2013	118000000
2014	117000000
2015	117000000
2016	116000000
2017	117000000
2018	120000000