Year	Percent
1960	1.70666
1961	2.103
1962	2.001
1963	2.01635
1964	1.92199
1965	1.73261
1966	2.22661
1968	2.65588
1969	2.50125
1970	2.11819
1971	1.70132
1972	1.42984
1973	1.36493
1974	1.58155
1975	1.71493
1976	1.56681
1977	1.25325
1978	0.85128
1979	0.6463
1980	0.77357
1981	0.74111
1982	0.54135
1983	0.34118
1984	0.59321
1985	1.00044
1986	0.90052
1987	0.89263
1988	0.43788
1989	0.43085
1990	0.44328
1991	0.62739
1992	0.64937
1993	0.68689
1994	0.69444
1995	0.75875
1996	0.64064
1997	0.66
1998	0.76788
1999	0.76803
2000	1.02115
2001	0.60871
2002	0.59965
2003	0.69758
2004	0.63451
2005	0.59819
2006	0.37105
2007	0.50925
2008	0.39844
2009	0.45535
2010	0.38068
2011	0.59226
2012	0.80417
2013	0.5334
2014	0.679
2015	0.52651
2016	0.38247
2017	0.40604