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	0
1995	0
1996	0
1997	0
1998	0
1999	5500
2000	10226
2001	17286
2002	21881
2003	81867
2004	116778
2005	227316
2006	1157102
2007	3268895
2008	4200000
2009	5597880
2010	9195562
2011	13354477
2012	16608622
2013	21362289
2014	23021340
2015	27516055
2016	32120305
2017	36096396
2018	39178451
2019	38696000
2020	38213000
2021	38213000