Year	Number
1960	16047
1961	16753
1962	17466
1963	18200
1964	18967
1965	19761
1966	20560
1967	21345
1968	22100
1969	22805
1970	23433
1971	23860
1972	24233
1973	24344
1974	24520
1975	24787
1976	24909
1977	24978
1978	24708
1979	24537
1980	24405
1981	24379
1982	24141
1983	23724
1984	23554
1985	23476
1986	23368
1987	24107
1988	23832
1989	23522
1990	23131
1991	23009
1992	22792
1993	22863
1994	23106
1995	23098
1996	23012
1997	23093
1998	23370
1999	23398
2000	23187
2001	22822
2002	23146
2003	22507
2004	22018
2005	21774
2006	21888
2007	21671
2008	21861
2009	21586
2010	21784
2011	20830
2012	20814
2013	21117
2014	21368
2015	21791
2016	22088
2017	22397
2018	22608
2019	22769
2020	22881
2021	22983
2022	27696
2023	27532