Year	Percent
1968-01-01	100.0000
1969-01-01	100.0000
1970-01-01	100.0000
1971-01-01	100.0000
1972-01-01	100.0000
1973-01-01	98.6143
1974-01-01	94.7537
1975-01-01	90.4659
1976-01-01	87.2112
1977-01-01	87.8618
1978-01-01	89.3757
1979-01-01	89.9223
1980-01-01	91.3182
1981-01-01	92.7387
1982-01-01	93.7948
1983-01-01	93.8433
1984-01-01	92.6980
1985-01-01	92.3635
1986-01-01	91.6877
1987-01-01	91.4871
1988-01-01	91.5519
1989-01-01	90.3163
1990-01-01	89.8616
1991-01-01	83.7431
1992-01-01	72.9575
1993-01-01	64.4324
1994-01-01	64.0255
1995-01-01	63.7908
1996-01-01	63.5416
1997-01-01	62.7017
1998-01-01	63.5210
1999-01-01	64.1953
2000-01-01	64.3418
2001-01-01	63.9526
2002-01-01	63.5050
2003-01-01	65.2639
2004-01-01	67.6465
2005-01-01	72.2335
2006-01-01	80.7502
2007-01-01	89.3383
2008-01-01	95.8643
2009-01-01	96.6226
2010-01-01	94.5948
2011-01-01	95.1098
2012-01-01	93.7352
2013-01-01	92.9607
2014-01-01	93.7475
2015-01-01	92.4576
2016-01-01	90.8158