Year	Percent
1970	0.45751
1971	0.36692
1972	0.41344
1973	0.07698
1974	0.11662
1975	0.08807
1976	0.09576
1977	0.21534
1978	0.17233
1979	0.28096
1980	0.25476
1981	0.2456
1982	0.14793
1983	0.27163
1984	0.92991
1985	0.62222
1986	1.11158
1987	1.25461
1988	2.40511
1989	2.49279
1990	1.96596
1991	-0.09384
1992	-0.67218
1993	1.57018
1994	3.03506
1995	1.41638
1996	2.43576
1997	4.40403
1998	14.32313
1999	7.3124
2000	22.52048
2001	6.14375
2002	5.2507
2003	0.12825
2004	1.39981
2005	5.12893
2006	0.82793
2007	6.46991
2008	10.62156
2009	-1.5539
2010	6.05029
2011	-1.29801
2012	3.2637
2013	-2.68298
2014	-0.06102
2015	-0.54601
2016	7.66517
2017	4.42872