Year	Number
1980	13558
1981	15755
1982	19537
1983	23982
1984	24764
1985	26069
1986	28031
1987	30762
1988	34681
1989	39832
1990	46826
1991	46612
1992	45124
1993	59593
1994	72581
1995	71852
1996	85062
1997	87065
1998	57393
1999	87332
2000	110073
2001	107137
2002	107876
2003	111114
2004	113814
2005	122133
2006	129327
2007	140272
2008	135882
2009	133116
2010	128672
2011	132506
2012	141838
2013	157139
2014	160310
2015	183004
2016	181888
2017	180312