Year	Percent
1972	0.07101
1973	0.22575
1974	0.57041
1975	1.88121
1976	-0.44071
1977	0.53565
1978	2.16814
1979	0.80603
1980	0.86523
1981	3.21149
1982	1.26976
1983	0.70857
1984	1.56014
1985	0.4996
1986	0.35546
1987	0.58468
1988	0.37806
1989	-0.03198
1990	0.90497
1991	-0.27364
1992	0.76671
1993	-0.59846
1994	0.04577
1995	0.19782
1996	0.22393
1997	4.98098
1998	3.91812
1999	1.93848
2000	10.79447
2001	3.04855
2002	2.48603
2003	5.36471
2004	8.20945
2005	15.76406
2006	23.53737
2007	15.32469
2008	12.86521
2009	10.13046
2010	6.38929
2011	5.15271
2012	5.00513
2013	5.79451
2014	6.08048
2015	4.26544
2016	4.01751
2017	5.06565