Year	Percent
1960-01-01	95.6875
1961-01-01	95.1206
1962-01-01	94.6175
1963-01-01	91.8228
1964-01-01	91.2776
1965-01-01	93.4707
1966-01-01	93.7910
1967-01-01	93.8596
1968-01-01	93.6342
1969-01-01	93.2649
1970-01-01	93.6618
1971-01-01	95.1572
1972-01-01	96.4780
1973-01-01	97.0951
1974-01-01	97.4149
1975-01-01	97.2635
1976-01-01	97.4042
1977-01-01	97.2115
1978-01-01	97.3018
1979-01-01	96.6672
1980-01-01	96.1927
1981-01-01	96.9943
1982-01-01	96.1395
1983-01-01	96.2360
1984-01-01	96.1334
1985-01-01	96.0736
1986-01-01	98.0405
1987-01-01	97.6585
1988-01-01	96.4305
1989-01-01	90.4157
1990-01-01	69.7067
1991-01-01	66.2641
1992-01-01	72.8507
1993-01-01	74.4750
1994-01-01	70.8296
1995-01-01	67.8043
1996-01-01	66.2228
1997-01-01	76.9233
1998-01-01	85.9518
1999-01-01	87.6973
2000-01-01	89.7225
2001-01-01	91.8335
2002-01-01	91.1959
2003-01-01	91.9419
2004-01-01	95.5794
2005-01-01	95.5479
2006-01-01	97.6441
2007-01-01	97.2094
2008-01-01	97.2022
2009-01-01	97.5419
2010-01-01	93.4808
2011-01-01	82.0852
2012-01-01	76.2700
2013-01-01	72.1863