Year	Percent
1966	55.14283
1967	54.9324
1968	54.93016
1969	54.43103
1970	53.02762
1971	52.41289
1972	51.74074
1973	49.29296
1974	44.50105
1975	44.6831
1976	45.09262
1977	44.85885
1978	44.67102
1979	47.01719
1980	47.83999
1981	46.84674
1982	46.48284
1983	45.01833
1984	45.9358
1985	45.9107
1986	45.30745
1987	43.73219
1988	47.31166
1989	47.57508
1990	53.46033
1991	53.73128
1992	53.67977
1993	55.39927
1994	62.39013
1995	59.55727
1996	57.21042
1997	50.86466
1998	51.30309
1999	51.02608
2000	51.24556
2001	53.06785
2002	50.77014
2003	50.8117
2004	50.2267
2005	50.78219
2006	51.55122
2007	52.86902
2008	52.98615
2009	50.58257
2010	51.42993
2011	50.91472
2012	50.95708
2013	52.91622
2014	53.02412
2015	53.97843
2016	48.35627