Year	% of total
1971	63.93817814158299
1972	68.04917759294099
1973	70.70627608234258
1974	72.38077589257193
1975	66.99821995075258
1976	67.99609002171123
1977	67.99908011360996
1978	66.0267494170903
1979	63.9786433077638
1980	66.33361801990306
1981	67.0320516283916
1982	66.76910378750966
1983	67.7744744028988
1984	67.35088966496537
1985	66.48772761376699
1986	67.82561327934292
1987	67.7026412188831
1988	67.47817529951465
1989	66.59543128091889
1990	67.3796645736493
1991	68.22121389434218
1992	70.80867713072251
1993	70.36132127028296
1994	69.18074733225711
1995	69.5103220656371
1996	69.90407976253583
1997	75.85067814744808
1998	77.26166213718848
1999	73.52906727782144
2000	76.01413925944843
2001	76.67612827434901
2002	74.94785653034145
2003	73.97276515168001
2004	74.92564059859848
2005	75.92287113091703
2006	75.27958214105776
2007	74.41022166849922
2008	74.97781639596327
2009	77.30712698474684
2010	76.95310386804442
2011	75.71843547803954
2012	75.54988014603619
2013	76.76212717572876
2014	76.68569262689398