Year	Percent
1977	2.83883
1978	-7.85168
1979	7.79245
1980	14.91276
1981	15.15134
1982	13.99288
1983	2.74508
1984	2.1116
1985	6.47507
1986	7.78129
1987	11.44697
1988	8.26611
1989	9.82405
1990	13.19075
1991	11.37469
1992	3.93529
1993	2.84782
1994	4.20557
1995	5.45405
1996	3.05364
1997	3.37112
1998	3.12891
1999	6.75967
2000	5.1937
2001	12.29515
2002	8.08542
2003	19.43814
2004	8.73952
2005	21.61664
2006	31.01283
2007	25.78957
2008	11.60335
2009	6.58742
2010	8.38888
2011	5.70562
2012	10.67904
2013	11.25712
2014	3.36079
2015	7.05329
2016	3.35153
2017	3.97336