Year	Percent
1971	4.36347
1972	1.50963
1973	1.4907
1974	2.82803
1975	3.34016
1976	2.67326
1977	2.95247
1978	2.71358
1979	1.61589
1980	2.13029
1981	3.14027
1982	1.69026
1983	2.1026
1984	2.38198
1985	1.69705
1986	1.52489
1987	1.10736
1988	2.02048
1989	2.43801
1990	1.79786
1991	2.79932
1992	1.30852
1993	2.08335
1994	5.05885
1995	3.75569
1996	8.2118
1997	2.22023
1998	7.21712
1999	20.77397
2000	17.25853
2001	9.62377
2002	-10.61438
2003	16.70413
2004	123.09966
2005	341.09504
2006	370.33714
2007	451.71554
2008	165.2798
2009	16.93358
2010	105.7852
2011	82.05377
2012	36.10202
2013	5.03108
2014	1.37135
2015	27.89424
2016	21.97901
2017	27.61071