Year	Percent
1961	10.97476
1962	2.79373
1963	3.77652
1964	12.20193
1965	12.31365
1966	5.3754
1967	0.87123
1968	0.14769
1969	5.97658
1970	-1.38253
1971	-3.2091
1972	4.66013
1973	1.32362
1974	2.46286
1975	0.1531
1976	-4.19808
1977	4.66109
1978	8.54982
1979	-7.54952
1980	11.2926
1981	-6.45087
1982	-6.99008
1983	-8.88872
1984	1.72361
1985	1.89673
1986	-1.76625
1987	-2.67403
1988	3.43148
1989	1.11172
1990	-2.89281
1991	-3.13833
1992	-6.18114
1993	-17.00906
1994	12.25629
1995	5.06058
1996	5.76249
1997	10.93908
1998	-5.31652
1999	-0.63326
2000	-3.67119
2001	-4.34803
2002	-3.55786
2003	2.2304
2004	-0.52307
2005	-1.4664
2006	1.29819
2007	-0.43154
2008	-0.50213
2009	0.75226
2010	1.23737
2011	2.11488
2012	2.06669
2013	1.25947
2014	3.14813
2015	2.71517
2016	2.77133
2017	2.97569