Year	Percent
1977	-11.01661
1978	-7.92108
1979	-16.45479
1980	-21.44048
1981	-20.79483
1982	-21.8277
1983	-31.13966
1984	-20.46918
1985	-16.53548
1986	-11.71966
1987	-15.79078
1988	-19.12791
1989	-21.7166
1990	-23.9461
1991	-16.67965
1992	-5.37392
1993	-10.15983
1994	-7.99139
1995	-17.91176
1996	-20.59944
1997	-15.6687
1998	-13.17388
1999	-15.2048
2000	-23.50617
2001	-19.29722
2002	-21.33602
2003	-19.47354
2004	-9.49148
2005	-9.84426
2006	-13.35727
2007	-16.80982
2008	-27.27751
2009	-26.38385
2010	-22.00333
2011	-14.99303
2012	-9.96918
2013	-6.99092
2014	5.25987
2015	1.45516
2016	0.45673