Year	Percent
1965	44.35127
1966	44.07436
1967	44.16718
1968	42.2437
1969	39.09281
1970	39.16605
1971	40.27249
1972	43.18647
1973	50.56298
1974	61.53144
1975	60.79655
1976	63.47862
1977	64.63877
1978	59.98798
1979	65.25505
1980	54.08567
1981	51.87362
1982	45.77562
1983	46.40156
1984	46.26287
1985	43.15371
1986	44.80782
1987	40.04501
1988	38.56912
1989	37.94415
1990	38.29754
1991	37.96401
1992	45.60155
1993	47.55796
1994	49.43105
1995	55.82862
1996	52.28279
1997	60.215
1998	58.64674
1999	58.53319
2000	66.93295
2001	64.2457
2002	64.59158
2003	67.06488
2004	70.19069
2005	68.77125
2006	71.05675
2007	75.44844
2008	80.38467
2009	63.5828
2010	70.01005
2011	75.29562
2012	72.9313
2013	73.99897
2014	70.02493
2015	68.2138
2016	63.77018
2017	65.92425