Year	Number
1970	10974
1971	11801
1972	12765
1973	13145
1974	13704
1975	14614
1976	15946
1977	16005
1978	16410
1979	16891
1980	17441
1981	17869
1982	18734
1983	19940
1984	19904
1985	20462
1986	20295
1991	25699
1992	26836
1993	28210
1994	28851
1998	32663
1999	34426
2000	35209
2001	36986
2002	38692
2003	40022
2004	42167
2005	43900
2006	45887
2007	46173
2008	46826
2009	48119
2010	48724
2011	49916
2012	52396
2013	51738
2014	49009
2015	52763
2016	45589
2017	44464
2018	44079
2019	42679
2020	41508