Year	Number
1970	1600
1971	1600
1972	1600
1973	1600
1974	1600
1975	3170
1976	3330
1977	3480
1978	3550
1979	3550
1980	3550
1981	3721
1982	3808
1983	3900
1984	3941
1985	5419
1986	6000
1987	7000
1988	8000
1989	9024
1990	13118
1991	14632
1992	15606
1993	16476
1994	17176
1995	18236
1996	19351
1997	20498
1998	21045
1999	23631
2000	24906
2001	26078
2002	27323
2003	21190
2004	19022
2005	22505
2006	22640
2007	22927
2008	22777
2009	23019
2010	21703
2011	22723
2012	19379
2013	19069
2014	23903
2015	24865
2016	20550
2017	20092
2018	19907
2019	17892
2020	17439
2021	12263
2022	11016