Year	Percent
1960	0.82131
1961	0.89074
1962	0.95378
1963	1.01584
1964	1.04079
1965	1.06834
1966	1.06565
1967	1.06719
1968	1.06013
1969	1.04401
1970	1.01589
1971	0.99833
1972	0.97632
1973	0.89475
1974	0.76436
1975	0.58152
1976	0.3845
1977	0.22119
1978	0.16263
1979	0.23679
1980	0.4064
1981	0.598
1982	0.77078
1983	0.90146
1984	0.98404
1985	1.01781
1986	1.05711
1987	1.09287
1988	1.07021
1989	0.96718
1990	0.81442
1991	0.63563
1992	0.48621
1993	0.39358
1994	0.39483
1995	0.46063
1996	0.5421
1997	0.60989
1998	0.65393
1999	0.69032
2000	0.70038
2001	0.71554
2002	0.73697
2003	0.75065
2004	0.74179
2005	0.73115
2006	0.72133
2007	0.70659
2008	0.68005
2009	0.64646
2010	0.61474
2011	0.57236
2012	0.53502
2013	0.50813
2014	0.48532
2015	0.48297
2016	0.47701
2017	0.46869