Year	Number
1970	35976
1971	34530
1972	34527
1973	33846
1974	34490
1975	29749
1976	29430
1977	29032
1978	28465
1979	27510
1980	25604
1981	24628
1982	23838
1983	22780
1984	21979
1986	22003
1987	21959
1988	23375
1991	23465
1994	28205
1995	27082
1996	27844
1997	28437
1998	29094
1999	31492
2000	32458
2001	33266
2002	33966
2003	34081
2004	34603
2005	35016
2006	35431
2007	35668
2008	35630
2010	35187
2011	35099
2012	35397
2013	35250
2014	35435
2015	35920
2016	36626
2017	37452
2018	38173
2019	39146
2020	40018
2021	40575