Year	Percent
1960	0.34613
1961	0.76046
1962	0.84866
1963	0.74837
1964	0.65026
1965	0.64247
1966	0.5513
1967	0.53854
1968	0.48677
1969	0.4158
1970	0.39872
1971	0.41767
1972	0.33906
1973	0.1932
1974	0.06306
1975	-0.00742
1976	-0.0246
1977	-0.03287
1978	0.00536
1979	0.08973
1980	0.11952
1981	0.03482
1982	-0.03584
1983	0.0341
1984	0.15826
1985	0.22695
1986	0.23161
1987	0.21264
1988	0.22206
1989	0.26031
1990	0.29893
1991	0.30925
1992	0.27043
1993	0.23975
1994	0.25459
1995	0.26455
1996	0.25463
1997	0.25755
1998	0.29141
1999	0.33341
2000	0.3573
2001	0.38498
2002	0.42334
2003	0.46564
2004	0.56894
2005	0.68661
2006	0.73505
2007	0.77867
2008	0.78703
2009	0.75639
2010	0.78389
2011	0.78168
2012	0.69532
2013	0.66953
2014	0.75335
2015	0.79497
2016	0.71403
2017	0.64841