Year	% of total
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0.35518243461414273
1978	0
1979	0.06450572488308337
1980	0
1981	0
1982	0
1983	0.6028075970272502
1984	1.14520628395243
1985	1.9435380905092918
1986	1.9633977546521761
1987	1.7105549510337321
1988	2.622911789214714
1989	2.9008514937220378
1990	2.2469158477974713
1991	2.814675950723085
1992	2.5919591453279693
1993	10.669603524229075
1994	36.44222905876397
1995	42.91216866859257
1996	43.12799007737287
1997	40.13694775349405
1998	34.853532894231016
1999	33.94867019728802
2000	27.95606750602732
2001	25.89527327315464
2002	22.034430819557002
2003	20.285198364225394
2004	16.335311202283563
2005	14.966007731574779
2006	14.614644703619092
2007	15.738193892410182
2008	16.880516453933005
2009	22.200109712069604
2010	23.708874554505023
2011	20.792511054046244
2012	22.72309153626956
2013	23.835755948523285
2014	24.58573961277186
2015	25.17009710065646