Year	Number
1960	14780
1961	15068
1962	15262
1963	15411
1964	15591
1965	15780
1966	15887
1967	16026
1968	16131
1969	16197
1970	16203
1971	15748
1972	15265
1973	14752
1974	14231
1975	13718
1976	13376
1977	13048
1978	12728
1979	12413
1980	12284
1981	12100
1982	11952
1983	11838
1984	11733
1985	11629
1986	11533
1987	11460
1988	11438
1989	11455
1990	11515
1991	11467
1992	11426
1993	11531
1994	11637
1995	11720
1996	11765
1997	11772
1998	11758
1999	11708
2000	11693
2001	11680
2002	11592
2003	11497
2004	11389
2005	11257
2006	11104
2007	10958
2008	10854
2009	10774
2010	10568
2011	10369
2012	10283
2013	10170
2014	10024
2015	9854
2016	9625
2017	9501
2018	9526
2019	9540
2020	9539
2021	9500
2022	9352
2023	9114