Year	Number
1981	16886
1982	16510
1983	17069
1984	20008
1985	17048
1986	19172
1987	19690
1988	19681
1989	22058
1990	24038
1991	26596
1992	28214
1993	32251
1994	41570
1995	46626
1999	73410
2000	81346
2001	92303
2002	102691
2003	92702
2004	79663
2005	93418
2006	108327
2007	135786
2008	138926
2009	157299
2010	183919
2011	205965
2012	208094
2013	215220
2014	231588
2015	291900
2016	310382
2017	286377