Year	Percent
1960	2.01893
1961	2.2997
1962	2.26365
1963	2.30535
1964	2.20853
1965	1.94095
1966	1.78875
1967	1.45946
1968	1.31237
1969	1.12917
1970	1.22616
1971	1.06239
1972	1.03782
1973	1.05369
1974	1.04271
1975	0.79775
1976	0.9335
1977	0.86091
1978	0.91697
1979	0.93376
1980	1.12403
1981	1.25881
1982	1.58173
1983	1.54522
1984	1.38112
1985	1.397
1986	1.11515
1987	0.83111
1988	0.71175
1989	0.71789
1990	0.62396
1991	0.55383
1992	0.61667
1993	0.51465
1994	0.37065
1995	0.43431
1996	0.28129
1997	0.22662
1998	0.31211
1999	0.41821
2000	0.79936
2001	0.97191
2002	1.28481
2003	1.36071
2004	1.29192
2005	1.33529
2006	1.09106
2007	1.04024
2008	0.94253
2009	0.97205
2010	0.85829
2011	0.91687
2012	0.90854
2013	0.87264
2014	0.81926
2015	0.84897
2016	0.86886
2017	0.85244