Year	Percent
1970	0.56619
1971	0.42845
1972	0.54818
1973	0.50043
1974	0.66106
1975	0.53163
1976	0.67676
1977	0.79163
1978	0.40349
1979	0.50771
1980	0.44583
1981	0.64553
1982	1.07459
1983	1.4083
1984	1.39075
1985	1.60442
1986	2.67071
1987	2.64943
1988	3.66121
1989	4.79149
1990	5.66675
1991	2.68617
1992	0.1494
1993	0.70045
1994	2.95713
1995	4.31689
1996	1.77432
1997	4.58205
1998	10.42276
1999	8.99907
2000	15.48591
2001	6.1634
2002	6.31494
2003	6.74783
2004	7.38366
2005	9.83888
2006	5.14314
2007	11.45745
2008	6.76399
2009	6.16185
2010	4.52986
2011	4.22191
2012	3.21673
2013	4.81962
2014	-0.66312
2015	3.26473
2016	0.34949
2017	6.81642