Year	Percent
1960	3.44986
1961	3.14453
1962	2.98348
1963	2.78902
1964	2.56027
1965	2.31166
1966	2.05948
1967	1.83018
1968	1.64534
1969	1.52528
1970	1.50285
1971	1.59975
1972	1.51663
1973	1.46451
1974	1.44291
1975	1.44208
1976	1.46435
1977	1.46277
1978	1.36542
1979	1.15528
1980	0.77363
1981	-0.10011
1982	-0.36174
1983	-0.59223
1984	-0.78143
1985	-0.92147
1986	-1.0789
1987	-1.21485
1988	-1.20025
1989	-0.97999
1990	-0.62019
1991	-0.17296
1992	0.21297
1993	0.40965
1994	0.33852
1995	0.08299
1996	-0.23109
1997	-0.48421
1998	-0.64137
1999	-0.66207
2000	-0.56835
2001	-0.44512
2002	-0.35846
2003	-0.74617
2004	-0.88916
2005	-0.9603
2006	-1.04552
2007	-1.10154
2008	-1.08266
2009	-0.95767
2010	-0.76253
2011	-0.54261
2012	0.53155
2013	0.66024
2014	0.75167
2015	0.77067
2016	0.77601
2017	0.79862