Year	Number
1971	16430
1972	16828
1973	17362
1974	17844
1975	21934
1976	22652
1977	23314
1978	24056
1979	24181
1980	24312
1981	27487
1982	27818
1983	27806
1984	27420
1986	25656
1987	24871
1988	22496
1992	20817
1993	21989
1994	23138
1995	25607
1996	27482
1997	28796
1998	29637
1999	32513
2000	32996
2001	33606
2002	34038
2003	34716
2004	35208
2005	35946
2006	37009
2007	38209
2008	39349
2010	42536
2011	43177
2012	44237
2013	46256
2014	46872
2015	47027
2016	47715
2017	48211
2018	48749
2019	48943
2020	49120
2021	49408