Year	Percent
1977	-0.13987
1978	1.5851
1982	1.51472
1983	1.89676
1984	1.92396
1985	2.45105
1986	2.38898
1987	6.84724
1988	6.33848
1989	3.92084
1990	4.62932
1991	5.07853
1992	7.28058
1993	6.53562
1994	5.93984
1995	5.83851
1996	4.62318
1997	8.54177
1998	10.91832
1999	8.62055
2000	7.19312
2001	11.28808
2002	10.08424
2003	15.08695
2004	10.85166
2005	10.08918
2006	12.85059
2007	20.63506
2008	16.32399
2009	13.29694
2010	7.83653
2011	5.47721
2012	3.93681
2013	8.86383
2014	6.62388
2015	8.65395
2016	8.64066
2017	7.09288