Year	Percent
1960	80.2244
1961	80.85761
1962	73.57791
1963	73.04711
1964	82.12253
1965	76.21892
1966	81.9136
1967	79.95658
1968	75.72703
1969	76.78471
1970	80.98403
1971	105.61411
1972	69.27907
1973	73.93509
1974	70.27803
1975	66.41918
1976	63.47453
1977	63.123
1978	52.38416
1979	63.81726
1980	68.86016
1981	60.42348
1982	55.69772
1983	52.45145
1984	50.44818
1985	63.03539
1986	70.09843
1987	74.40874
1988	54.23288
1989	56.34419
1990	76.98121
1991	56.26121
1992	48.74413
1993	49.95054
1994	41.59548
1995	45.70447
1996	52.04017
1997	40.29483
1998	60.26543
1999	55.37095
2000	49.44392
2001	50.53761
2002	49.09163
2003	52.1038
2004	59.92047
2005	52.42248
2006	53.65452
2007	61.35349
2008	56.72074
2009	53.12797
2010	61.78513
2011	68.96277
2012	71.24472
2013	75.56723
2014	71.74951
2015	73.35741
2016	67.04994
2017	65.33861