Year	Percent
1980	-51.57361
1981	-42.65158
1982	-35.67268
1983	-34.23841
1984	-9.77137
1985	4.7973
1986	7.329
1987	11.53827
1988	7.1763
1989	5.2233
1990	2.82637
1991	-5.93147
1992	-5.27943
1993	-12.59676
1994	-1.4744
2006	-17.101
2007	9.00211
2008	-4.71967
2009	9.89922
2010	12.14108
2011	5.29026
2012	11.71156
2013	15.45252
2014	14.75159
2015	9.38189
2016	-1.19981
2017	-4.79505