Year	Number
1972	4957
1975	7423
1976	7779
1980	10215
1981	10898
1982	10742
1986	13954
1987	14237
1988	15450
1989	16052
1990	16603
1991	16529
1992	15393
1993	14118
1994	13510
1995	12938
1996	12818
1997	13171
1998	11541
1999	11007
2000	11341
2001	11910
2002	12910
2003	14536
2004	14662
2005	15141
2006	16207
2010	19043
2014	20908
2015	20875
2016	21753
2017	21709
2018	21234
2019	22144