Year	Number
1960	0
1965	0
1970	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	0
1991	0
1992	0
1993	0
1994	144
1995	230
1996	337
1997	658
1998	702
1999	1093
2000	1151
2001	967
2002	999
2003	1060
2004	3000
2005	6000
2006	7000
2007	10900
2008	30000
2009	50000
2010	115500
2011	274872
2012	302147
2013	323105
2014	376696
2015	424712
2016	416572
2017	465331
2018	482029
2019	478116
2020	474000
2021	474000