Year	% of total
1960	4.280533609636057
1961	5.406408511691204
1962	8.31209453197405
1963	10.548428659458855
1964	11.911942098914356
1965	10.012813472451034
1966	7.8208016321672975
1967	8.935676392572944
1968	9.848216045732308
1969	11.352331006825281
1970	7.028710725893824
1971	12.30054606056308
1972	14.634399308556612
1973	14.063915124854445
1974	9.19024098188894
1975	11.161366043569117
1976	15.456163518401562
1977	11.913309044149164
1978	13.161875945537066
1979	12.650197775953428
1980	13.956730769230768
1981	7.49893481039625
1982	6.859239966852136
1983	7.43114457257219
1984	6.170943042987783
1985	4.787161080883362
1986	5.323237146690316
1987	4.262598615359845
1988	3.215020041953104
1989	2.8277896450005087
1990	3.8136968516715353
1991	4.443913034813973
1992	3.982859088087467
1993	5.316229000798116
1994	4.998944560649383
1995	3.836674036753779
1996	3.600627169895845
1997	4.293795456586155
1998	4.981219817563942
1999	4.434541691701716
2000	2.842636202692321
2001	2.9770579854913453
2002	2.385266695219583
2003	3.203263507582147
2004	2.9379479563504876
2005	2.5446989315676025
2006	2.6346209421057702
2007	2.040460134867116
2008	1.9278154008275348
2009	1.7130104348875081
2010	1.8753496040274382
2011	1.628340184994861
2012	1.0813564255566874
2013	1.0766847405112316
2014	0.9786419111918983
2015	1.39403850201577