Year	Number
1971	12697
1972	12979
1973	13875
1974	15116
1975	16133
1976	16962
1977	17794
1978	19654
1979	20589
1980	22185
1981	23718
1982	24647
1983	27785
1984	26409
1985	28253
1986	30707
1987	32241
1988	33246
1989	34313
1990	33826
1991	40778
1992	42435
1993	45120
1994	47417
1995	48944
1996	49794
1997	49897
1998	50744
1999	49874
2000	50915
2001	50829
2002	51324
2003	52274
2004	54261
2005	55907
2006	58567
2008	65849
2009	69974
2010	73548
2011	76149
2012	76937
2013	81896
2014	83000
2015	85788
2016	89302
2017	91304
2018	92483