Year	Percent
1970	0.22938
1971	0.00943
1972	0.18262
1973	-0.06324
1974	0.04559
1975	0.22046
1976	0.06163
1977	0.10064
1978	0.18111
1979	0.29559
1980	0.26861
1981	0.38463
1982	0.20775
1983	0.10267
1984	0.17819
1985	0.42186
1986	0.33145
1987	0.38792
1988	0.48474
1989	0.52426
1990	0.613
1991	0.56854
1992	0.69184
1993	0.67709
1994	0.8113
1995	1.19175
1996	1.45606
1997	1.14723
1998	0.81361
1999	0.8448
2000	0.41648
2001	0.52275
2002	1.14235
2003	0.64148
2004	1.14108
2005	2.01001
2006	3.11298
2007	3.66832
2008	3.19736
2009	1.3904
2010	1.13975
2011	0.62082
2012	0.38283
2013	0.57651
2014	0.76444
2015	0.59914
2016	0.89286
2017	0.9231