Year	Number
1991	1900
1992	4100
1993	9200
1994	12000
1995	13300
1996	15000
1997	16700
1998	16800
1999	15900
2000	16955
2001	18258
2002	19340
2003	19751
2004	20482
2005	22031
2006	21641
2007	22391
2008	24728
2009	24613
2010	24766
2011	26743
2012	26456
2013	24305
2014	25161
2015	25183
2016	26171
2017	26809
2018	27189
2019	27711
2020	12838
2021	15982