Year	Percent
1973	0.49383
1976	0.48997
1977	0.519
1979	0.51381
1980	0.52865
1981	0.56913
1984	0.61619
1985	0.60781
1986	0.62878
1987	0.62473
1988	0.71792
1989	0.7274
1990	0.7544
2005	1.05402
2006	1.0565
2007	1.06504
2008	1.08614
2009	1.06029
2010	1.08659
2011	1.09395
2013	1.0601
2015	1.10128
2016	1.08078