Year	% of total
1960	88.81955575910236
1961	95.04821813833797
1962	95.97514789970049
1963	93.23648898190325
1964	94.94287856733271
1965	94.56712161336321
1966	89.85658975979773
1967	91.57221953847869
1968	86.70877068137342
1969	72.04367744824498
1970	68.46821572381016
1971	78.17356539513632
1972	75.00453574867765
1973	76.69997437868307
1974	76.241512448409
1975	71.56619326646143
1976	63.46883970738031
1977	59.44615452999811
1978	62.1775547995349
1979	64.25009993057455
1980	61.119647825906384
1981	58.099488555704646
1982	55.336039874587996
1983	58.36739567737372
1984	55.08810072362657
1985	51.99100623265148
1986	44.12314243503954
1987	49.2187125369065
1988	47.979621123172734
1989	50.2015169750063
1990	49.66503178430513
1991	43.026467986663945
1992	50.93465628768775
1993	51.39589802199013
1994	41.41555711282411
1995	45.923947859979904
1996	36.792365619688965
1997	46.282321086283396
1998	47.231896014257735
1999	46.30064971131117
2000	54.109659783379584
2001	48.92478108852378
2002	45.23517382413088
2003	39.54823126186484
2004	39.63988316971379
2005	45.97164777570802
2006	43.07678349594517
2007	44.454822171304166
2008	46.07856218394332
2009	48.20649468536792
2010	44.724504917149396
2011	44.21446350845901
2012	47.424835972986614
2013	40.09710450823689
2014	41.52545684254399
2015	46.5086981492117