Year	Percent
1960	2.29863
1961	2.00112
1962	1.85989
1963	1.86285
1964	1.88571
1965	1.81017
1966	1.86281
1967	1.79936
1968	1.61341
1969	1.35978
1970	1.39783
1971	1.4966
1972	1.59537
1973	1.69414
1974	1.7929
1975	1.89168
1976	1.3226
1977	1.17514
1978	1.00352
1979	0.99767
1980	1.29324
1981	1.2406
1982	1.20556
1983	1.00281
1984	0.96173
1985	0.92945
1986	1.00488
1987	1.31177
1988	1.29106
1989	1.78359
1990	1.49359
1991	1.36051
1992	1.22742
1993	1.09433
1994	0.96124
1995	0.82816
1996	1.07716
1997	1.05702
1998	0.86561
1999	0.82737
2000	0.883
2001	1.00952
2002	0.89713
2003	0.99623
2004	1.00203
2005	0.9859
2006	0.79684
2007	0.96985
2008	1.0822
2009	1.14484
2010	1.11396
2011	0.98762
2012	1.18034
2013	1.14968
2014	1.08359
2015	0.83277
2016	1.19865
2017	1.21548