Year	Percent
1960	2.50759
1961	2.3695
1962	2.23961
1963	2.11707
1964	1.92909
1965	1.8218
1966	1.68484
1967	1.55417
1968	1.42908
1969	1.40895
1970	1.38937
1971	1.43512
1972	1.38288
1973	1.36402
1974	1.28347
1975	1.11353
1976	1.00996
1977	0.849
1978	0.81191
1979	0.80537
1980	0.88732
1981	0.96704
1982	1.01553
1983	1.0339
1984	1.02332
1985	0.95695
1986	0.89237
1987	0.85695
1988	0.74044
1989	0.57213
1990	0.40667
1991	0.21622
1992	0.05398
1993	-0.13501
1994	-0.27056
1995	-0.43174
1996	-0.20022
1997	-0.36985
1998	-0.0404
1999	-0.15702
2000	-0.20336
2001	-0.22363
2002	-0.23158
2003	-0.28159
2004	-0.24745
2005	-0.24331
2006	-0.27792
2007	-0.23175
2008	-0.19035
2009	-0.12624
2010	-0.09986
2011	-0.05782
2012	-0.01312
2013	-0.02678
2014	-0.06097
2015	-0.06438
2016	-0.06062
2017	-0.06207