Year	Percent
1960	1.81567
1961	1.53595
1962	1.26849
1963	0.99584
1964	0.76408
1965	0.54599
1966	0.31036
1967	0.0906
1968	-0.09798
1969	-0.19625
1970	-0.27074
1971	-0.25555
1972	-0.26685
1973	-0.32416
1974	-0.51183
1975	-0.75862
1976	-1.09961
1977	-1.37982
1978	-1.23958
1979	-0.56856
1980	0.49219
1981	1.74526
1982	2.74324
1983	3.06144
1984	2.52451
1985	1.47927
1986	0.23694
1987	-0.76483
1988	-1.3351
1989	-1.22404
1990	-0.60678
1991	0.17744
1992	0.76839
1993	1.13248
1994	1.11275
1995	0.85145
1996	0.53817
1997	0.3229
1998	0.18475
1999	0.1312
2000	0.17433
2001	0.22608
2002	0.24614
2003	0.26898
2004	0.27411
2005	0.28501
2006	0.30067
2007	0.31618
2008	0.33154
2009	0.35154
2010	0.36464
2011	0.3795
2012	0.38565
2013	0.40494
2014	0.42493
2015	0.43437
2016	0.46138
2017	0.47225