Year	Number of
1980	31247
1981	32572
1982	24853
1983	22795
1984	14531
1985	15017
1986	13180
1987	14631
1988	15371
1989	15489
1990	14437
1991	15216
1992	14446
1993	15145
1994	16353
1995	11329
1996	20722
1997	23575
1998	21514
1999	19802
2000	18434
2001	18879
2002	17790
2003	19231
2004	15101
2005	18524
2006	17934
2007	18440
2008	18810
2009	18957
2010	20155
2011	19857
2012	20470
2013	20708
2014	21196
2015	21600
2016	22193
2017	22757
2018	23271
2019	23702
2020	17603