Year	Percent
1960	1.94857
1961	2.22173
1962	2.65867
1963	2.57416
1964	2.65254
1965	2.69804
1966	2.5994
1967	2.76579
1968	2.80554
1969	2.43971
1970	2.52892
1971	2.42419
1972	2.13548
1973	2.1111
1974	2.08004
1975	2.04757
1976	2.00249
1977	1.95321
1978	1.86732
1979	1.76544
1980	1.66809
1981	1.3818
1982	0.92193
1983	0.80498
1984	0.73069
1985	0.67412
1986	0.60956
1987	0.56647
1988	0.51559
1989	0.45806
1990	0.40088
1991	0.48915
1992	0.59827
1993	0.62693
1994	0.58438
1995	0.54952
1996	0.52456
1997	0.52573
1998	0.52034
1999	0.51171
2000	0.55341
2001	0.80023
2002	1.66116
2003	2.12807
2004	2.04276
2005	2.00176
2006	1.99921
2007	2.1577
2008	1.89845
2009	1.18538
2010	0.75661
2011	0.64939
2012	0.35558
2013	-0.03533
2014	-0.00494
2015	0.21933
2016	0.38297
2017	0.48921