Year	Percent
1970	-26.18874
1971	-30.15384
1972	-31.27459
1973	-34.66665
1974	-34.23006
1975	-20.76181
1976	-22.66276
1977	-23.29785
1978	-28.31842
1979	-34.25424
1980	-29.15434
1981	-24.5254
1982	-33.44496
1983	-26.24458
1984	-37.88021
1985	-47.95154
1986	-26.59989
1987	-27.58915
1988	-38.7273
1989	-37.2988
1990	-27.09852
1991	-27.80864
1992	-45.2094
1993	-23.84743
1994	-17.85496
1995	-23.47609
1996	-21.31136
1997	-18.86637
1998	-21.39915
1999	-17.95529
2000	-11.36164
2001	-5.62838
2002	-5.51816
2003	-5.912
2004	-7.92533
2005	-9.01892
2006	-14.75187
2007	-13.75975
2008	-12.94083
2009	-16.3732
2010	-20.31824
2011	-5.27299
2012	-10.22257
2013	-7.56601
2014	-11.17821
2015	-4.69545
2016	-4.796
2017	-4.23259