Year	Number of
1968	4957
1969	4973
1970	4962
1971	4906
1972	4829
1973	4758
1974	4687
1975	4666
1976	4689
1977	4756
1978	4817
1979	4893
1980	4905
1981	4852
1982	4773
1983	4658
1984	4552
1985	4446
1986	4357
1987	4248
1988	4138
1989	4045
1990	3933
1991	3865
1992	3813
1993	3790
1994	3771
1995	3750
1996	3729
1997	3690
1998	3684
1999	3532
2000	3443
2001	3345
2002	3244
2003	3105
2004	2989
2005	2880
2006	2778
2007	2666
2008	2557
2009	2428
2010	2294
2011	2170
2012	2059
2013	1953
2014	1861
2015	1787