Year	Number
1960	5358
1961	5739
1962	6272
1963	6878
1964	7606
1965	8395
1966	9267
1967	10242
1968	11304
1969	12434
1970	13743
1971	15173
1972	16795
1973	18412
1974	20024
1975	21632
1976	23241
1977	24853
1978	26470
1979	28094
1980	29512
1981	30922
1982	32314
1983	33670
1984	34977
1985	36221
1986	36703
1987	35543
1988	34327
1989	33097
1990	31862
1991	30626
1992	29395
1993	28176
1994	26967
1995	25767
1996	24579
1997	23901
1998	23891
1999	23888
2000	23829
2001	23718
2002	23592
2003	23444
2004	22638
2005	22100
2006	23641
2007	25660
2008	26878
2009	26795
2010	25685
2011	25222
2012	24831
2013	24731
2014	25068
2015	25474
2016	25562
2017	25002
2018	23932
2019	22795
2020	21117
2021	19409
2022	18381
2023	17548