Year	Number
1970	25934
1971	26722
1972	27205
1973	27691
1974	28236
1975	29259
1976	30361
1977	31544
1978	32993
1979	34368
1980	35771
1981	37287
1982	38859
1983	40669
1984	41127
1985	41225
1986	40746
1987	40504
1988	40234
1989	39936
1990	39520
1991	39336
1992	38997
1993	38544
1994	38297
1995	38110
1996	37910
1997	37584
1998	37408
1999	37470
2000	37468
2001	37555
2002	37259
2003	36843
2004	36368
2005	36163
2006	37162
2007	38351
2008	39389
2009	40207
2010	40847
2011	40553
2012	40163
2013	40458
2014	40765
2015	41359
2016	41371
2017	41364
2018	41304
2019	41175
2020	40685
2021	40236
2022	39828