Year	Number
1960	-1845
1961	-469
1962	1376
1963	3544
1964	5663
1965	8091
1966	10636
1967	13608
1968	16791
1969	20270
1970	24024
1971	27272
1972	29789
1973	31535
1974	32613
1975	32971
1976	32630
1977	31478
1978	29717
1979	27325
1980	24210
1981	21737
1982	20102
1983	19123
1984	18758
1985	19149
1986	20357
1987	22282
1988	24900
1989	28219
1990	32373
1991	35486
1992	37760
1993	38984
1994	39389
1995	38760
1996	37200
1997	34673
1998	31182
1999	26897
2000	21650
2001	17665
2002	14789
2003	13122
2004	12819
2005	13610
2006	15632
2007	18739
2008	23206
2009	28780
2010	35628
2011	41782
2012	46924
2013	51268
2014	54876
2015	57677
2016	59528
2017	60585
2018	60758
2019	60266
2020	58816
2021	57439
2022	29998
2023	29998