Year	Percent
1971	4.70532
1972	4.20936
1973	5.74323
1974	8.94845
1975	1.73915
1976	12.67237
1977	6.08605
1978	7.35853
1979	8.64885
1980	9.21033
1981	9.67397
1982	6.38842
1983	3.89802
1984	3.75561
1985	2.96292
1986	2.51873
1987	3.17101
1988	3.32115
1989	4.1299
2003	5.98273
2004	6.87841
2005	12.75112
2006	-2.08589
2007	2.50212
2008	-12.33914
2009	5.92941
2010	2.31078
2011	6.37378
2012	13.67631
2013	-2.42297
2014	-2.78408
2015	3.68926