Year	Number
1960	16200
1961	16323
1962	16393
1963	16459
1964	16530
1965	16607
1966	16677
1967	16747
1968	16825
1969	16906
1970	17060
1971	17306
1972	17569
1973	17823
1974	18068
1975	18297
1976	18511
1977	18709
1978	18895
1979	19079
1980	19262
1981	19510
1982	19828
1983	20103
1984	20302
1985	20427
1986	20476
1987	20468
1988	20381
1989	20205
1990	19937
1991	19757
1992	19798
1993	19893
1994	19955
1995	20002
1996	20043
1997	20083
1998	20119
1999	20140
2000	20137
2001	20206
2002	20396
2003	20604
2004	20787
2005	20961
2006	21124
2007	21283
2008	21436
2009	21576
2010	21683
2011	21881
2012	22229
2013	22411
2014	23000
2015	23626
2016	23846
2017	24214
2018	24563
2019	24946
2020	25284
2021	25516
2022	25683
2023	25809