Year	Percent
1960	2.35516
1961	4.81781
1962	5.07641
1963	5.09722
1964	4.79537
1965	4.30228
1966	3.86304
1967	3.38281
1968	3.14103
1969	3.26473
1970	3.42134
1971	3.14734
1972	3.47707
1973	3.62491
1974	3.51552
1975	3.24607
1976	3.02317
1977	2.79689
1978	2.61643
1979	2.50236
1980	3.66261
1981	6.77526
1982	6.00984
1983	5.31216
1984	4.70077
1985	4.14886
1986	3.67372
1987	3.25095
1988	2.88474
1989	2.55749
1990	2.00146
1991	0.8837
1992	0.81822
1993	1.01037
1994	1.09358
1995	1.08499
1996	1.27856
1997	1.08259
1998	0.72466
1999	0.64608
2000	0.37091
2001	0.15691
2002	0.07062
2003	0.0053
2004	-0.03901
2005	-0.20372
2006	-0.48299
2007	-0.64625
2008	-0.64731
2009	-0.60716
2010	-0.56904
2011	-1.21199
2012	-1.26012
2013	-1.18861
2014	-1.67049
2015	-1.78964
2016	-1.96134
2017	-2.07263