Year	Percent
1960	63.39904
1961	60.87398
1962	60
1963	60.95455
1964	74.10012
1965	74.25171
1966	59.87726
1967	57.67196
1968	51.56392
1969	53.86592
1970	54.37993
1971	54.81249
1972	55.0765
1973	56.01048
1974	73.65708
1975	68.92473
1976	61.32542
1977	62.01248
1978	57.64786
1979	58.87612
1980	74.22317
1981	72.66183
1982	67.25673
1983	58.57288
1984	48.78204
1985	39.90266
1986	32.71044
1987	25.62127
1988	24.38625
1989	27.82202
1990	44.44502
1991	44.95204
1992	33.77163
1993	22.24295
1994	26.39926
1995	27.20736
1996	30.76036
1997	34.79364
1998	52.48561
1999	33.63414
2000	33.19901
2001	54.42705
2002	39.58868
2003	45.55462
2004	48.11527
2005	45.1566
2006	48.16687
2007	47.2522
2008	52.2582
2009	43.79583
2010	38.41407
2011	50.68874
2012	52.07497
2013	52.97686
2014	52.91431
2015	55.98205
2016	54.31929
2017	60.64197