Year	% of total
1960	1.4126532705487436
1961	1.3140775435857404
1962	1.2016782761008595
1963	1.0991017308113633
1964	0.9498455268520344
1965	0.8846119362840321
1966	0.7894151656659996
1967	0.7450607609896462
1968	0.6752550165221972
1969	0.6161334882803078
1970	0.5285433668819992
1971	0.49580544820435485
1972	0.5037511469334148
1973	0.5247550884165748
1974	0.6163527434162321
1975	0.6645917992905584
1976	0.6335741962509164
1977	0.5200819523076363
1978	0.4720609832855444
1979	0.46114978542193
1980	0.40426738349749036
1981	0.39527238572323103
1982	0.49419133632785195
1983	0.40846498668461
1984	0.3955015066724064
1985	0.3810797258900217
1986	0.3669022285322316
1987	0.35735194604745935
1988	0.5285840311221022
1989	0.5507132075984825
1990	0.4861070602189426
1991	0.491260796238565
1992	0.4210499855460453
1993	0.4171873851356318
1994	0.41096136245356496
1995	0.43170047162987185
1996	0.538146946834015
1997	0.5449098845010104
1998	0.5461006363482532
1999	0.5868573421009984
2000	0.5860938512560515
2001	0.7129957862350345
2002	0.8782731838612355
2003	1.063077439184717
2004	1.1274554911420471
2005	2.0994363840996377
2006	2.456096628238236
2007	2.7467394301565156
2008	3.2159063326654955
2009	2.740885547874806
2010	3.2677487918116297
2011	3.827385617568637
2012	5.007008936393902
2013	5.984672763910088
2014	7.500886153449554
2015	8.341657549667826