Year	Number
1980	80033
1981	60447
1982	55947
1983	62563
1984	47596
1985	51977
1986	40688
1987	31708
1988	38014
1989	30901
1990	28634
1991	24455
1992	21749
1993	18673
1994	17325
1995	17294
1996	19662
1997	19698
1998	18877
1999	18911
2000	20504
2001	18971
2002	18398
2003	17949
2004	16500
2005	16811
2006	18074
2007	18056
2008	17286
2009	15559
2010	16058
2011	16820
2012	19030
2013	20358
2014	21940
2015	22930
2016	23906
2017	24727