Year	Percent
1973	1.88489
1974	1.47154
1975	1.62879
1976	1.61389
1977	2.15223
1978	1.58816
1979	1.74743
1980	1.87685
1981	2.03915
1982	2.00306
1983	1.89514
1984	1.60402
1985	1.58837
1986	1.79553
1987	1.67523
1988	1.59426
1989	1.75376
1990	3.72917
1991	5.50917
1992	4.2906
1993	4.53638
1994	3.43788
1995	0.6078
1996	0.87225
1997	0.85442
1998	0.91644
1999	0.85254
2000	0.71734
2001	0.7048
2002	0.65364
2003	0.60957
2004	0.56095
2005	0.54652
2006	0.61509
2007	0.56209
2008	0.61723
2009	0.70708
2010	0.67839
2011	0.66718
2012	0.67481
2013	0.72204
2014	0.80096
2015	0.92758
2016	0.97769
2017	0.97452