Year	Percent
1970	0.05557
1971	0.03848
1972	0.01252
1973	0.01156
1974	0.04861
1975	0.03054
1976	0.0717
1977	0.11299
1978	0.17624
1979	0.0859
1980	0.31736
1981	0.10168
1982	0.07442
1983	0.26925
1984	0.06013
1985	0.02006
1986	0.09158
1987	0.07148
1988	0.11221
1989	0.07334
1990	0.03973
1991	0.05892
1992	0.10146
1993	0.43009
1994	0.18232
1995	0.27695
1996	0.33751
1997	0.75888
1998	0.80858
1999	0.13405
2000	0.32572
2001	0.01641
2002	0.87485
2003	0.99033
2004	0.16438
2005	3.27191
2006	0.77972
2007	0.61654
2008	1.26449
2009	1.49886
2010	1.91021
2011	2.51027
2012	-0.16399
2013	2.01269
2014	1.03093
2015	1.44681
2016	1.61282
2017	1.19329