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	0.1463057790782736
1991	0.15914530862669973
1992	0.16133569407442955
1993	0.15398291900815952
1994	0.18420172203614046
1995	0.20319229610923037
1996	0.33438845364222497
1997	0.3821651914722289
1998	0.4105697626714074
1999	0.7926122444101865
2000	1.1659167120460863
2001	3.020017777344844
2002	3.5889617584350435
2003	3.5982971902541316
2004	4.9719578890859015
2005	4.667607863375952
2006	4.354015982372173
2007	3.481097255513347
2008	6.214651443527611
2009	2.86020153565276
2010	7.072293478366247
2011	4.719260865395284
2012	8.461449376067634
2013	12.082381946292742
2014	13.7263798757642
2015	13.66624717184846