Year	% of total
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	1.0293049164446597
1979	1.0680034873583262
1980	1.3334660165190566
1981	1.3619938849254145
1982	1.2052283143778646
1983	1.8811725975858284
1984	2.400698384984723
1985	14.681477516059957
1986	17.74223544727543
1987	19.11486137420355
1988	20.824720959073996
1989	18.996049267952593
1990	24.070212026416407
1991	29.097619764989453
1992	40.332207783348686
1993	49.45738219292438
1994	53.135549872122766
1995	58.985526373674716
1996	63.55803640889995
1997	70.13285420589811
1998	70.11085305793019
1999	73.98096055677341
2000	73.63800447621111
2001	71.42113555793146
2002	67.42447709733464
2003	70.9031592093693
2004	66.52569150746196
2005	66.87431204867369
2006	66.27073360792608
2007	63.34857869477829
2008	63.83881555403319
2009	61.24151961587201
2010	56.73312711361852
2011	44.98781666988977
2012	46.62042997149894
2013	48.978662503252664
2014	50.06882802487303
2015	46.60311877593706