Year	Percent
1975	-29.48828
1976	-29.6947
1977	-23.31121
1978	-39.08309
1979	-43.72496
1980	-37.65634
1981	-41.86991
1982	-37.03692
1983	-50.51289
1984	-36.347
1985	-42.10214
1986	-44.16346
1987	-33.67885
1988	-44.01263
1989	-37.70239
1990	-31.22537
1991	-37.65547
1992	-25.34689
1993	-27.65535
1994	-28.91648
1995	-38.36266
1996	-38.02518
1997	-30.53257
1998	-39.69977
1999	-19.91076
2000	-24.5791
2001	-32.11374
2002	-37.00741
2003	-37.24214
2004	-37.25874
2005	-38.96681
2006	-37.11814
2007	-45.75182
2008	-36.21769
2009	-49.96724
2010	-47.83976
2011	-45.37924
2012	-43.74577
2013	-42.22667
2014	-40.60819
2015	-47.70186
2016	-46.80601