Year	Percent
1970	0.24972
1971	0.21943
1972	0
1973	0.22188
1974	0.54521
1975	0.52169
1976	0.53616
1977	0.30137
1978	0.1413
1979	0.08217
1980	0.39297
1981	0.28347
1982	0.48284
1983	0.58141
1984	0.97245
1985	1.97684
1986	2.03716
1987	0.93104
1988	0.94989
1989	1.31124
1990	1.22441
1991	1.46315
1992	-0.09187
1993	0.59574
1994	1.70353
1995	1.88073
1996	3.99593
1997	3.49042
1998	2.91354
1999	2.99067
2000	6.30589
2001	1.10942
2002	3.96071
2003	2.92101
2004	2.88428
2005	10.27948
2006	5.36198
2007	5.71578
2008	7.85337
2009	2.57825
2010	6.97737
2011	2.60533
2012	5.23078
2013	1.76344
2014	4.53625
2015	5.72457
2016	2.18048
2017	1.70989