Year	Percent
1971	0.60676
1972	0.60386
1973	0.60785
1974	0.60919
1975	0.61908
1976	0.6405
1977	0.65135
1978	0.66343
1979	0.68082
1980	0.69012
1981	0.70755
1982	0.72755
1983	0.74112
1984	0.76107
1985	0.77855
1986	0.79072
1987	0.80054
1988	0.8087
1989	0.82449
1990	0.83889
1991	0.8544
1992	0.87085
1993	0.88525
1994	0.90262
1995	0.91418
1996	0.92716
1997	0.93702
1999	0.96208
2000	0.98083
2001	0.98501
2002	0.98354
2003	1.0027
2005	1.02049
2006	1.02277
2008	1.01924
2009	1.02033
2010	1.0189
2011	1.00893
2016	1.03789