Year	Number
1971	17243
1972	21049
1973	27073
1974	32348
1975	39064
1976	41802
1977	45572
1978	51273
1979	55434
1980	64275
1981	83207
1982	99295
1983	117724
1984	115362
1985	112267
1986	99345
1987	95121
1988	85753
1990	77500
1995	116300
1996	128256
1997	146135
2000	208885
2001	233177
2002	262950
2003	283560
2004	313986
2005	377618
2006	433850
2011	699101
2013	846328
2014	873090
2015	941689
2016	965124