Year	Percent
1960	1.0436
1961	0.60296
1962	0.22459
1963	0.03842
1964	0.12347
1965	0.40342
1966	0.7446
1967	1.01988
1968	1.20778
1969	1.26516
1970	1.2311
1971	1.17265
1972	1.14393
1973	1.12564
1974	1.13164
1975	1.14792
1976	1.19011
1977	1.20842
1978	1.15375
1979	0.99908
1980	0.79024
1981	0.5481
1982	0.36629
1983	0.34277
1984	0.52307
1985	0.85201
1986	1.22231
1987	1.53779
1988	1.79461
1989	1.95835
1990	2.05192
1991	2.1314
1992	2.20753
1993	2.24073
1994	2.21755
1995	2.1595
1996	2.08695
1997	2.01399
1998	1.94595
1999	1.89088
2000	1.84413
2001	1.78575
2002	1.72249
2003	1.68456
2004	1.6814
2005	1.69262
2006	1.72214
2007	1.72608
2008	1.66425
2009	1.51523
2010	1.31464
2011	1.09304
2012	0.90509
2013	0.77527
2014	0.73278
2015	0.7501
2016	0.78418
2017	0.80233