Year	Number
1960	9725
1961	10081
1962	10499
1963	10905
1964	11295
1965	11685
1966	12064
1967	12439
1968	12836
1969	13268
1970	13705
1971	14110
1972	14493
1973	14863
1974	15238
1975	15661
1976	16138
1977	16635
1978	17140
1979	17655
1980	18286
1981	19066
1982	19907
1983	20781
1984	21687
1985	22617
1986	23568
1987	24527
1988	25492
1989	26464
1990	27284
1991	27901
1992	28471
1993	29045
1994	29630
1995	30219
1996	30810
1997	31411
1998	32006
1999	32588
2000	32997
2001	33167
2002	33248
2003	33301
2004	33351
2005	33435
2006	33542
2007	33645
2008	33710
2009	33691
2010	33669
2011	33647
2012	33521
2013	33300
2014	33003
2015	32646
2016	32236
2017	31783
2018	31297
2019	30760
2020	30184
2021	29563
2022	29039
2023	28657