Year	Percent
1960	1.08059
1961	0.91666
1962	0.88298
1963	0.90291
1964	0.87505
1965	0.89971
1966	0.87942
1967	0.83623
1968	0.79387
1969	0.77255
1970	0.77323
1971	0.82412
1972	0.84248
1973	0.81501
1974	0.86207
1975	0.90739
1976	0.89165
1977	0.89068
1978	0.89129
1979	0.90739
1980	0.90679
1981	0.91665
1982	0.92638
1983	0.9523
1984	0.9584
1985	0.9594
1986	0.96281
1987	0.96551
1988	0.94971
1989	0.94078
1990	0.94179
1991	0.94082
1992	0.94831
1993	0.95066
1994	0.92287
1995	0.91688
1996	0.91125
1997	0.92044
1998	0.93859
1999	0.94525
2000	0.93114
2001	0.94708
2002	0.95583
2003	0.95567
2004	0.94161
2005	0.93158
2006	0.9172
2007	0.89763
2008	0.92025
2009	0.98378
2010	0.95885
2011	0.98681
2012	0.96743
2013	0.95087
2014	0.96733
2015	0.96065
2016	0.94216
2017	0.93496