Year	% of total
1960	71.62454873646209
1961	69.8645598194131
1962	72.30046948356808
1963	68.16053511705685
1964	64.83656792645557
1965	63.97263744616164
1966	51.41078421528265
1967	61.437586274896475
1968	54.7287899860918
1969	38.77899045020464
1970	31.207550938873354
1971	18.594286941580755
1972	18.751822688830565
1973	35.80020920502092
1974	30.85286565043982
1975	34.94853263250109
1976	46.47715637037398
1977	48.014865844815084
1978	55.39230091096091
1979	63.11790511510108
1980	81.84195778068373
1981	85.99402924657188
1982	91.45241507207284
1983	94.98173948329502
1984	95.8318630910374
1985	93.56299752950865
1986	92.51534938115194
1987	93.82820712808166
1988	91.08656929105807
1989	89.08559717437754
1990	90.67046416750057
1991	91.51730742919688
1992	87.69926475372503
1993	86.32189321245659
1994	82.03952880871408
1995	74.42189455356657
1996	74.02672539285581
1997	64.88999210199707
1998	57.531680976819985
1999	51.59558067831449
2000	46.24580478739633
2001	47.22892204935196
2002	46.47084277241836
2003	54.79366041657645
2004	46.17914729449006
2005	42.66125917342603
2006	53.85981451842758
2007	50.59263404212025
2008	47.689534629670085
2009	48.61336338399802
2010	43.75997118007308
2011	39.67186125067416
2012	34.32787205628481
2013	41.136344011743375
2014	34.37733035048471
2015	24.544857843645282