Year	% of total
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0.35303878131012695
1984	2.1353233144905555
1985	4.124154780544038
1986	10.145860145860146
1987	17.20528651360216
1988	18.36664905026891
1989	19.066189679261793
1990	20.210049621814328
1991	20.120070317423462
1992	20.742672333508306
1993	21.527943533262864
1994	22.22507664114816
1995	20.18984729673958
1996	20.133807561537374
1997	19.45590731426258
1998	20.391804902203518
1999	20.81859131220873
2000	18.63916281493876
2001	19.86825443866692
2002	24.656885321402726
2003	31.240340030911902
2004	31.41783029001074
2005	30.181494184130546
2006	31.135391015372843
2007	29.82088327788159
2008	31.87586289693259
2009	33.330066640533126
2010	32.818360840210055
2011	32.59311330321748
2012	34.98102368290517
2013	35.74667472793229
2014	35.63622261915953
2015	32.48886414253897