Year	Percent
1971	10.53918
1972	13.38514
1973	15.27257
1974	6.08761
1975	20.13335
1976	21.02293
1977	13.26859
1978	10.52645
1979	13.67606
1980	14.7048
1981	17.44254
1982	15.18216
1983	10.70888
1984	6.37927
1985	5.18633
1986	6.5497
1987	2.19741
1988	3.24631
1989	5.52176
1990	-0.72918
1991	1.8014
1992	2.81222
1993	5.17575
1994	1.69453
1995	3.034
1996	1.88335
1997	4.45653
1998	6.71422
1999	4.25086
2000	6.79227
2001	6.35351
2002	4.86187
2003	3.82374
2004	0.55486
2005	2.81935
2006	3.01236
2007	1.32069
2008	-0.88886
2009	-5.01048
2010	-3.22141
2011	-0.37443
2012	2.06857
2013	1.04236
2014	-0.39784
2015	7.28003
2016	0.02073
2017	-0.30837