Year	Number
1980	708
1981	656
1982	829
1983	1070
1984	1181
1985	1312
1986	1430
1987	1528
1988	2179
1989	2730
1990	4963
1991	10100
1992	16175
1993	24299
1994	30799
1995	33293
1996	29869
1997	33360
1998	34526
1999	36213
2000	41252
2001	41616
2002	42953
2003	47498
2004	53975
2005	54284
2006	57989
2007	55608
2008	54603
2009	46247
2010	48144
2011	47903
2012	43207
2013	45818
2014	45094
2015	44441
2016	45834
2017	45714