Year	Percent
1960	2.90346
1961	2.79605
1962	2.69323
1963	2.64167
1964	2.65699
1965	2.68682
1966	2.77612
1967	2.78041
1968	2.52855
1969	1.95855
1970	1.199
1971	0.36295
1972	-0.34922
1973	-0.80577
1974	-0.88487
1975	-0.67193
1976	-0.35635
1977	-0.08887
1978	0.1146
1979	0.18464
1980	0.17989
1981	0.15094
1982	0.1944
1983	0.34772
1984	0.64397
1985	1.03095
1986	1.44242
1987	1.78488
1988	1.9966
1989	2.04867
1990	1.97785
1991	1.88266
1992	1.80129
1993	1.70642
1994	1.6142
1995	1.51849
1996	1.41248
1997	1.30643
1998	1.22201
1999	1.17236
2000	1.14692
2001	1.12617
2002	1.10411
2003	1.08878
2004	1.07907
2005	1.07116
2006	1.06873
2007	1.06469
2008	1.06221
2009	1.05643
2010	1.04785
2011	1.03736
2012	1.02708
2013	1.01203
2014	0.98821
2015	0.95902
2016	0.92842
2017	0.89752