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
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	0.010945356915212114
1991	0.011068068622025456
1992	0.017372369445317483
1993	0.01705631805381447
1994	0.054403740391814656
1995	0.30607770107370275
1996	0.1518181144930756
1997	0.25874029833927287
1998	0.2453104925053533
1999	0.24444987487166583
2000	0.23411603126857844
2001	0.225125915882316
2002	0.20959227742835657
2003	0.1905006136317843
2004	0.1786247527798931
2005	0.29730458242583585
2006	0.3871660187148852
2007	0.47678248760584924
2008	0.859573400323317
2009	1.29233409626383
2010	1.6738524026947463
2011	2.1376401980844917
2012	2.6575149877666444
2013	3.5648783506208974
2014	4.056659803785733
2015	4.857004208305114