Year	Percent
1971	7.84587
1972	8.51808
1973	11.84943
1974	15.9452
1975	16.7818
1976	16.48986
1977	23.38309
1978	20.63104
1979	16.93169
1980	13.35481
1981	12.35117
1982	13.58235
1983	11.88424
1984	10.86473
1985	8.59546
1986	10.87882
1987	5.9442
1988	5.93612
1989	6.89621
1990	7.32624
1991	6.93515
1992	6.71077
1993	4.53723
1994	3.87985
1995	4.93312
1996	0.79718
1997	2.22816
1998	1.49956
1999	2.73198
2000	29.22628
2001	2.76952
2002	3.40041
2003	2.87986
2004	3.35037
2005	3.0996
2006	3.20049
2007	3.86981
2008	1.98007
2009	-0.00001
2010	1.59994
2011	2.49987
2012	1.09991
2013	0.00036
2014	-0.10037
2015	-0.45547
2016	0.6999
2017	0.89993