Year	Number
1970	12009
1971	12563
1972	13724
1973	13908
1974	14434
1975	13572
1976	13788
1977	13685
1978	13821
1979	13698
1980	14768
1981	18017
1982	16821
1983	17036
1984	15021
1985	14193
1986	16212
1988	15188
1989	15827
1990	15827
1991	15747
1992	16378
1993	16991
1994	15793
1995	16991
1996	16868
1997	16869
1998	17724
1999	17929
2000	17384
2001	17307
2002	17235
2003	17547
2004	17834
2005	18139
2006	18600
2007	23175
2008	23555
2009	24931
2010	24785
2011	25575
2012	15940
2013	27343
2014	28060
2015	26943
2016	27832
2017	27616
2018	27762
2019	25054
2020	26181
2021	20537
2022	19528