Year	Percent
1970	0.48788
1971	0.92617
1972	1.1872
1973	0.3329
1974	0.61881
1975	1.00804
1976	1.58215
1977	1.2049
1978	-0.19326
1979	0.27681
1980	0.41342
1981	1.08198
1982	0.90228
1983	-1.25053
1984	1.07511
1985	-0.53351
1986	-0.20124
1987	-0.07855
1988	0.2997
1989	0.54552
1990	0.99522
1991	-0.13441
1992	0.3561
1993	-0.0143
1994	1.72486
1995	0.64923
1996	0.17218
1997	3.76709
1998	1.40387
1999	2.97911
2000	1.74034
2001	0.92349
2002	1.54305
2003	1.2583
2004	1.71001
2005	1.92807
2006	3.09426
2007	3.11038
2008	3.3775
2009	2.57625
2010	2.09923
2011	2.35025
2012	1.94144
2013	2.096
2014	2.63037
2015	2.99734
2016	3.21467
2017	3.25062