Year	Percent
1970	1.63401
1971	3.11487
1972	2.48484
1973	2.45996
1974	1.03435
1975	1.69236
1976	0.93366
1977	1.22245
1978	0.57746
1979	0.6551
1980	-1.15086
1981	0.88795
1982	0.83781
1983	1.02798
1984	0.66372
1985	1.68173
1986	0.93244
1987	2.53413
1988	1.62712
1989	7.77614
1990	1.91137
1991	2.60058
1992	3.06011
1993	8.52092
1994	10.83256
1995	3.78069
1996	4.55431
1997	4.29745
1998	3.28492
1999	2.80149
2000	2.458
2001	2.69749
2002	3.17011
2003	2.96405
2004	2.13336
2005	4.43885
2006	3.33794
2007	3.6263
2008	3.93892
2009	5.0476
2010	1.63285
2011	2.14724
2012	1.53376
2013	1.08024
2014	0.8182
2015	0.65216
2016	1.0985
2017	0.93068