Year	Percent
1960	34.17099
1961	31.21169
1962	31.71426
1963	47.103
1964	41.89187
1965	43.24324
1966	39.73511
1967	48.05391
1968	48.42248
1969	54.65546
1970	49.72066
1971	66.3177
1972	73.08744
1973	58.84543
1974	57.54641
1975	49.52422
1976	45.58476
1977	51.59374
1978	61.75816
1979	58.48588
1980	64.72019
1981	63.36351
1982	61.59475
1983	61.32477
1984	59.09266
1985	62.57248
1986	35.19131
1987	42.69492
1988	36.73058
1989	45.79558
1990	46.0385
1991	47.26346
1992	46.07555
1993	48.79461
1994	61.67564
1995	59.387
1996	62.66324
1997	61.30401
1998	47.40635
1999	59.6125
2000	69.03218
2001	54.27523
2002	52.6089
2003	51.92943
2004	55.03916
2005	60.00867
2006	60.57182
2007	58.5286
2008	62.19971
2009	52.17138
2010	57.66294
2011	61.74373
2012	60.95021
2013	57.35803
2014	44.52121
2015	45.93638
2016	44.12798
2017	43.73524