Year	Percent
1970	0.28422
1971	0.37746
1972	0.20649
1973	0.19079
1974	0.02474
1975	0.10601
1976	0.47818
1977	0.25361
1978	0.43042
1979	0.29746
1980	0.88096
1981	1.06385
1982	0.26925
1983	0.17792
1984	0.33885
1985	1.0394
1986	0.51742
1987	-0.0171
1988	0.90883
1989	1.34139
1990	1.29888
1991	1.28558
1992	1.93671
1993	1.1798
1994	1.41195
1995	2.17393
1996	2.5532
1997	3.12788
1998	2.43877
1999	8.46058
2000	3.66579
2001	0.80616
2002	2.19896
2003	1.29481
2004	2.50502
2005	2.64935
2006	2.38107
2007	2.25129
2008	2.6899
2009	1.20644
2010	2.67516
2011	2.04464
2012	2.80667
2013	1.77921
2014	0.96241
2015	1.97713
2016	0.58756
2017	1.80631