Year	Number
1981	23831
1986	25729
1989	28675
1990	28679
1991	28793
1992	28176
1993	29443
1994	28675
1995	28429
1996	28530
1997	29852
1998	25082
1999	24849
2000	24819
2001	24386
2002	24492
2003	24767
2004	24989
2005	25124
2006	25202
2008	18575
2009	18396
2010	16375
2011	16380
2012	15798
2013	15242
2014	14800
2015	14661
2016	14369
2017	14189
2018	13986
2019	13436
2020	13121
2021	13130
2022	13075