Year	Number
1960	15663
1961	15900
1962	16013
1963	16070
1964	16081
1965	16050
1966	15976
1967	15863
1968	15706
1969	15486
1970	15353
1971	15300
1972	15321
1973	15340
1974	15353
1975	15373
1976	15399
1977	15429
1978	15458
1979	15469
1980	15464
1981	15357
1982	15246
1983	15122
1984	14990
1985	14853
1986	14710
1987	14561
1988	14405
1989	14239
1990	14064
1991	13976
1992	14022
1993	14131
1994	14240
1995	14346
1996	14449
1997	14554
1998	14663
1999	14777
2000	14901
2001	14991
2002	15015
2003	15003
2004	14985
2005	14965
2006	14946
2007	14924
2008	14903
2009	14878
2010	14848
2011	14837
2012	14825
2013	14791
2014	14760
2015	14732
2016	14714
2017	14705
2018	14699
2019	14695
2020	14694
2021	14713
2022	14769
2023	14850