Year	Percent
1960	3.1859
1961	3.1929
1962	3.19963
1963	3.21366
1964	3.238
1965	3.26887
1966	3.29707
1967	3.32003
1968	3.3429
1969	3.36578
1970	3.38703
1971	3.41043
1972	3.42991
1973	3.43595
1974	3.42643
1975	3.40864
1976	3.37856
1977	3.35549
1978	3.36396
1979	3.41113
1980	3.47581
1981	3.54287
1982	3.58128
1983	3.57065
1984	3.50178
1985	3.39626
1986	3.28521
1987	3.18898
1988	3.10441
1989	3.03704
1990	2.98251
1991	2.92204
1992	2.86045
1993	2.81936
1994	2.80263
1995	2.7978
1996	2.81656
1997	2.82098
1998	2.76014
1999	2.61814
2000	2.43486
2001	2.14641
2002	1.8964
2003	1.89765
2004	2.22241
2005	2.70352
2006	3.33475
2007	3.72479
2008	3.46715
2009	2.42756
2010	0.92698
2011	-0.7394
2012	-2.14757
2013	-3.04056
2014	-3.10723
2015	-2.46785
2016	-1.63884
2017	-0.87512