Year	Percent
1960	0.00285
1961	54.00909
1962	54.53878
1963	78.52066
1964	69.8406
1965	73.92786
1966	67.9962
1967	69.11371
1968	64.29325
1969	68.91659
1970	69.06349
1971	70.79412
1972	85.30125
1973	71.97785
1974	71.19697
1975	65.43403
1976	54.42688
1977	73.30595
1978	72.14806
1979	78.54392
1980	66.52432
1981	78.76199
1982	83.69247
1983	79.17375
1984	76.79453
1985	84.01412
1986	62.78576
1987	61.4907
1988	51.81897
1989	56.4923
1990	52.45037
1991	56.95069
1992	49.74617
1993	71.71168
1994	74.11439
1995	72.49671
1996	72.72516
1997	77.49469
1998	67.33703
1999	69.37606
2000	70.02165
2001	70.25818
2002	66.74381
2003	65.68767
2004	65.43058
2005	68.23317
2006	69.53439
2007	68.06037
2008	78.20844
2009	65.12018
2010	81.26462
2011	73.84936
2012	76.41493
2013	78.40931
2014	72.24491
2015	60.06203
2016	46.61836
2017	53.76603