Year	Number
1971	4937
1972	5012
1973	4811
1974	4930
1975	6366
1976	6956
1977	6514
1978	6940
1979	7461
1980	8193
1981	8537
1982	9150
1983	6305
1984	8656
1985	9766
1987	8804
1988	9813
1989	9381
1990	9164
1991	11432
1992	12672
1993	9915
1994	13807
1995	18780
1996	18693
1997	20939
1998	21737
1999	26784
2000	33100
2001	33627
2002	37304
2003	37898
2004	39669
2005	42196
2006	45422
2007	54693
2008	75267
2009	89032
2010	104666
2011	94406
2013	109899
2014	129115
2015	122805
2016	131308
2017	132303
2018	127718