Year	Number
1970	8300
1971	7700
1972	8300
1973	8800
1974	4700
1975	5400
1976	6200
1977	6300
1978	7200
1979	8300
1980	9500
1981	10000
1982	8700
1983	9500
1984	10100
1985	10500
1986	9600
1987	8800
1988	9400
1989	10000
1990	10900
1991	10000
1992	12900
1993	14700
1994	15200
1995	13400
1996	15400
1997	14400
1998	12300
1999	20900
2000	21303
2001	20492
2002	19752
2003	28508
2004	32488
2009	69808
2010	62473
2011	60778.7162603187
2012	63711.9791706662
2013	52452
2014	55980
2015	57444
2016	55592
2017	54474
2018	57094
2019	57321
2020	17591
2021	29475