Year	% of total
1960	22.97788972851945
1961	21.148036253776436
1962	22.063037249283667
1963	17.9637787567303
1964	18.052095130237827
1965	20.335195530726256
1966	16.776007497656984
1967	16.524378675773097
1968	15.021682567215958
1969	16.22112211221122
1970	12.81581358816599
1971	12.741000404476205
1972	10.49221183800623
1973	8.841902931283038
1974	11.783397325566002
1975	10.121107266435986
1976	11.607254534083802
1977	8.556591526023839
1978	8.431703204047219
1979	10.719640179910044
1980	10.060711188204682
1981	8.856155664666304
1982	8.753907994640464
1983	9.583414824955995
1984	10.785824345146379
1985	10.924975231919301
1986	8.420314690761801
1987	9.251418791099901
1988	8.813120414328873
1989	7.492945195306698
1990	11.214489726027397
1991	10.922978723404254
1992	9.561898193760262
1993	10.074804870433967
1994	11.11971190971191
1995	11.743262839879154
1996	11.211004405286344
1997	10.88528623289584
1998	10.835872635225154
1999	10.236304292608585
2000	11.685334507042255
2001	10.290373778033352
2002	8.936118363794604
2003	8.07095635775862
2004	9.387754938601175
2005	8.106318394281
2006	7.22406852248394
2007	8.03845
2008	8.79407337469652
2009	5.679198931909212
2010	6.946801242236026
2011	7.989604083665339
2012	7.922820250575299
2013	7.69676524470034
2014	8.42030564263323
2015	8.057150621118012
2016	7.575567852437418