Year	Number
1975	15900
1976	16000
1977	16500
1978	17200
1979	29900
1980	32000
1981	8200
1982	9200
1983	9100
1984	8400
1985	18100
1986	18000
1987	18300
1988	19500
1989	20200
1990	18900
1991	18900
1992	16700
1993	17700
1994	17700
1995	19300
1996	20100
1997	9100
1998	9300
1999	31100
2000	31416
2001	29395
2002	26493
2003	24455
2004	29817
2005	33211
2006	33723
2007	34402
2008	33433
2009	30267
2010	26395
2011	28393
2012	30640
2013	34188
2014	53366
2015	48535
2016	49095
2017	48017
2018	54000
2019	47733
2020	31284.792
2021	27092.684