Year	Percent
1960	45.82783
1961	34.58008
1962	36.58884
1963	38.70557
1964	61.93786
1965	62.8978
1966	67.98672
1967	78.7283
1968	84.3145
1969	89.22928
1970	74.31143
1971	73.72422
1972	74.65406
1973	85.25241
1974	83.62169
1975	69.89879
1976	78.28376
1977	68.20102
1978	69.71163
1979	68.00416
1980	71.77859
1981	69.4613
1982	62.38909
1983	59.14682
1984	55.51115
1985	54.85754
1986	55.17475
1997	8.78675
1998	10.78977
1999	14.5541
2000	31.37613
2001	33.97313
2002	42.35727
2003	36.05769
2004	67.62166
2005	59.09091
2006	82.44639
2007	74.96341
2008	34.39249
2009	15.26438
2010	19.13908
2011	21.80743
2012	32.91271
2013	34.57972
2014	28.43202
2015	19.46903
2016	21.41837