Year	Percent
1976	8.02874
1977	8.89689
1978	11.07304
1979	13.1367
1980	14.15334
1981	12.38885
1982	10.3526
1983	5.0446
1984	8.18192
1985	5.66771
1986	4.15067
1987	3.86185
1988	3.19369
1989	4.75174
1990	5.43312
1991	3.88801
1992	6.04138
1993	4.80313
1994	5.27098
1995	12.27198
1996	2.50272
1997	3.97623
1998	3.36284
1999	2.55531
2000	3.86088
2001	3.65717
2002	0.71437
2003	3.95117
2004	3.55312
2005	4.02717
2006	3.47577
2007	3.18615
2008	4.02442
2009	0.02342
2010	2.0081
2011	1.909
2012	1.89271
2013	-1.05104
2014	-1.5652
2015	-1.18262
2016	-0.68444
2017	1.52089