Year	Percent
1970	0.52156
1971	0.49911
1972	1.51776
1973	1.41049
1974	1.21723
1975	1.45112
1976	1.12862
1977	1.73017
1978	1.37202
1979	1.05849
1980	1.61118
1981	-0.99156
1982	0.97627
1983	0.79905
1984	0.62786
1985	2.25753
1986	1.70282
1987	3.28209
1988	2.51238
1989	4.09389
1990	6.17006
1991	1.01513
1992	1.41424
1993	9.60517
1994	1.0939
1995	2.54789
1996	3.25529
1997	4.81958
1998	5.59688
1999	4.75867
2000	3.37991
2001	3.54135
2002	7.11495
2003	7.07897
2004	5.85172
2005	4.28403
2006	4.82713
2007	9.41811
2008	5.24051
2009	4.53278
2010	8.5332
2011	4.72504
2012	6.7893
2013	7.48713
2014	5.55346
2015	7.4815
2016	3.16307
2017	3.35509