Year	Percent
1960-01-01	76.600
1961-01-01	76.390
1962-01-01	76.735
1963-01-01	79.710
1964-01-01	78.565
1965-01-01	80.430
1966-01-01	83.510
1967-01-01	85.825
1968-01-01	87.175
1969-01-01	88.265
1970-01-01	85.300
1971-01-01	85.750
1972-01-01	86.540
1973-01-01	87.080
1974-01-01	87.590
1975-01-01	85.850
1976-01-01	85.690
1977-01-01	83.540
1978-01-01	83.835
1979-01-01	85.040
1980-01-01	85.040
1981-01-01	83.605
1982-01-01	82.910
1983-01-01	82.560
1984-01-01	81.920
1985-01-01	82.640
1986-01-01	80.415
1987-01-01	81.730
1988-01-01	80.590
1989-01-01	82.765
1990-01-01	82.340
1991-01-01	82.580
1992-01-01	80.870
1993-01-01	81.695
1994-01-01	81.000
1995-01-01	81.535
1996-01-01	83.300
1997-01-01	86.490
1998-01-01	85.920
1999-01-01	87.720
2000-01-01	88.020
2001-01-01	89.525
2002-01-01	89.340
2003-01-01	90.080
2004-01-01	91.700
2005-01-01	92.210
2006-01-01	93.650
2007-01-01	94.850
2008-01-01	95.360
2009-01-01	95.395
2010-01-01	94.940
2011-01-01	94.680
2012-01-01	95.020
2013-01-01	95.330
2014-01-01	95.790
2015-01-01	96.220