Year	Number
1970	25200000
1971	25900000
1972	26900000
1973	28000000
1974	28800000
1975	29800000
1976	30500000
1977	31700000
1978	32800000
1979	34500000
1980	36800000
1981	38700000
1982	41200000
1983	44600000
1984	47400000
1985	49700000
1986	52000000
1987	53000000
1988	54300000
1989	55800000
1990	59900000
1991	65100000
1992	70400000
1993	75400000
1994	78200000
1995	80300000
1996	82600000
1997	85600000
1998	86200000
1999	86000000
2000	90500000
2001	92400000
2002	96700000
2003	102000000
2004	105000000
2005	110000000
2006	114000000
2007	120000000
2008	126000000
2009	126000000
2010	134000000
2011	141000000
2012	147000000
2013	149000000
2014	160000000
2015	162000000
2016	166000000
2017	163000000
2018	165000000