Year	Percent
1961	7.97546
1962	23.38308
1963	24.29907
1964	23.9819
1965	23.45133
1966	25.61983
1967	52.57732
1968	73.82465
1969	77.2
1970	77.24719
1971	75.77938
1972	71.02273
1973	70.83825
1974	82.51539
1975	77.53387
1976	69.73877
1977	66.19137
1978	61.78551
1979	64.21869
1980	69.36257
1981	67.12798
1982	63.29807
1983	60.6993
1984	59.09285
1985	59.28991
1986	51.34932
1987	56.76899
1988	46.4258
1989	49.11477
1990	54.09646
1991	49.40378
1992	48.78757
1993	45.7053
1994	45.107
1995	46.4849
1996	49.36588
1997	48.62304
1998	40.79895
1999	47.28872
2000	59.15527
2001	56.401
2002	55.47392
2003	55.55529
2004	56.26575
2005	63.53443
2006	63.70104
2007	61.11866
2008	66.93583
2009	59.60398
2010	64.08543
2011	71.64909
2012	70.47173
2013	67.54583
2014	63.96837
2015	54.66862
2016	47.17366