Year	Percent
1971	0.16203
1972	0.1503
1973	0.20625
1974	0.29238
1975	0.34621
1976	0.38359
1977	0.40839
1978	0.42998
1979	0.46206
1980	0.47316
1981	0.50316
1982	0.53805
1983	0.57649
1984	0.63223
1985	0.69057
1986	0.74465
1987	0.77953
1988	0.80767
1989	0.82956
1990	0.84837
1991	0.88774
1992	0.91103
1993	0.93972
1994	0.96303
1995	0.97184
1996	0.95731
1997	0.98543
1998	0.99049
1999	0.98852
2000	0.97855
2001	0.98097
2002	0.9679
2003	0.95996
2005	0.97573
2006	0.99356
2007	0.99202
2008	0.98464
2009	0.95715
2011	0.98562
2012	0.99572
2013	1.03662
2015	1.0131
2016	0.98796