Year	Percent
1977	-19.7556
1978	-22.13841
1979	-62.95987
1980	-70.56464
1981	-44.12998
1982	-28.32322
1983	-19.41613
1984	-32.77134
1985	-23.40897
1986	-5.88896
1987	-8.10811
1988	-14.14071
1989	-31.26705
1990	-25.99149
1991	-18.84519
1992	-13.3211
1993	-12.45357
1994	-13.7381
1995	-14.5958
1996	-10.0235
1997	-14.5266
1998	-7.96371
1999	-8.8809
2000	-11.48344
2001	-12.96936
2002	-9.79192
2003	-11.11876
2004	-11.64264
2005	-18.1
2006	-13.94687
2007	-20.99967
2008	-28.50092
2009	-23.82393
2010	-17.99691
2011	-15.2755
2012	-18.83044
2013	-9.99958
2014	-11.83923
2015	-8.74468
2016	-5.63713
2017	-11.99913