Year	Percent
1971	0.79231
1972	0.84189
1973	0.83984
1974	0.84259
1975	0.84468
1976	0.8611
1977	0.86402
1978	0.86412
1979	0.87949
1980	0.89603
1981	0.89944
1982	0.92108
1983	0.93355
1984	0.93785
1985	0.93693
1986	0.93466
1987	0.92292
1988	0.92624
1989	0.9336
1990	0.95002
1992	0.99481
1993	1.00741
1994	1.0193
1995	1.04387
1996	1.02287
1997	1.01663
1998	1.01344
1999	1.00365
2000	1.019
2001	1.03801
2003	1.06228
2004	1.07086
2005	1.06782
2006	1.04003
2007	1.01508
2008	1.02667
2009	1.01558
2010	1.00612
2011	0.98727
2012	1.04175
2013	1.04288
2014	1.05053
2015	1.06094