Year	Percent
1960	0.66528
1961	0.69814
1962	0.77845
1963	0.78773
1964	0.79921
1965	0.77924
1966	0.80301
1967	0.78842
1968	0.60883
1969	0.55299
1970	0.75142
1971	0.6949
1972	0.57199
1973	0.60449
1974	0.46559
1975	0.28827
1976	0.25135
1977	0.31145
1978	0.3106
1979	0.24563
1980	0.1216
1981	-0.02841
1982	-0.07348
1983	-0.06867
1984	-0.05238
1985	0.04053
1986	0.13373
1987	0.12666
1988	0.04859
1989	0.05999
1990	0.16246
1991	0.25952
1992	0.33067
1993	0.33317
1994	0.33771
1995	0.52096
1996	0.56593
1997	0.41556
1998	0.36316
1999	0.33089
2000	0.33423
2001	0.35832
2002	0.31949
2003	0.27201
2004	0.25843
2005	0.27548
2006	0.32865
2007	0.44347
2008	0.58755
2009	0.53508
2010	0.4442
2011	0.41174
2012	0.37627
2013	0.4169
2014	0.50705
2015	0.70642
2016	0.78039
2017	0.72351