Year	Number
1980	8785
1981	9292
1982	12238
1983	15617
1984	15924
1985	18962
1986	20446
1987	22175
1988	24201
1989	26918
1990	33564
1991	33468
1992	33163
1993	46559
1994	56319
1995	55218
1996	66441
1997	66222
1998	42901
1999	71262
2000	90596
2001	86408
2002	90014
2003	92368
2004	91936
2005	99436
2006	105544
2007	112157
2008	107488
2009	108170
2010	106896
2011	112578
2012	120341
2013	135233
2014	138046
2015	160026
2016	157113
2017	155665