Year	Percent
1968	21.08645
1969	3.58936
1970	6.02974
1971	6.69544
1972	6.47231
1973	3.95723
1974	4.81805
1975	22.98914
1976	10.94634
1977	8.06395
1978	8.56215
1979	11.42125
1980	14.50165
1981	10.80851
1982	13.1537
1983	10.8174
1984	9.252
1985	-3.48249
1986	-0.1383
1987	-1.90653
1988	-4.25293
1989	3.41538
1990	7.60211
1991	-5.81606
1992	0.73882
1993	3.23509
1994	39.56235
1995	15.80898
1996	-1.65212
1997	5.5802
1998	1.73958
1999	16.28605
2000	-0.61973
2001	4.67836
2002	3.51288
2003	-7.59428
2004	3.59862
2005	7.50173
2006	4.64687
2007	4.55505
2008	6.75151
2009	5.17546
2010	4.3681
2011	12.15342
2012	4.60482
2013	0.70115
2014	1.55068
2015	2.78635
2016	1.53037
2017	1.54254