Year	Percent
1991	-19.1846
1992	-17.39467
1993	-27.06157
1994	-18.29219
1995	-19.58069
1996	-17.56812
1997	-15.98711
1998	-16.71984
1999	-17.45026
2000	-20.71926
2001	-23.77946
2002	-23.87374
2003	-31.96864
2004	-29.30257
2005	-28.89993
2006	-30.54003
2007	-27.09373
2008	-30.86197
2009	-26.86427
2010	-49.40701
2011	-41.52397
2012	-36.25362
2013	-34.03545
2014	-34.21553
2015	-30.53696
2016	-31.89821
2017	-37.651