Year	Number
1970	48221
1973	52670
1974	53586
1975	55263
1976	66986
1977	70647
1978	74032
1979	77929
1980	86560
1981	94614
1982	145389
1983	133393
1984	162005
1985	179483
1986	213733
1987	242727
1988	262735
1990	267517
1991	256194
1992	256669
1993	261762
1994	275590
1995	292321
1997	294418
2004	732792
2007	1031520
2010	1264942
2011	1254005
2012	1296816
2013	1421237
2014	1460569
2016	1520562
2017	1434278