Year	Percent
1991-01-01	88.6790008544922
1992-01-01	88.1480026245117
1993-01-01	87.5380020141602
1994-01-01	86.8570022583008
1995-01-01	86.1119995117188
1996-01-01	85.3720016479492
1997-01-01	84.5630035400391
1998-01-01	83.6780014038086
1999-01-01	82.9830017089844
2000-01-01	82.2509994506836
2001-01-01	81.6790008544922
2002-01-01	81.1380004882813
2003-01-01	80.6360015869141
2004-01-01	80.1780014038086
2005-01-01	79.7669982910156
2006-01-01	79.3669967651367
2007-01-01	78.9929962158203
2008-01-01	78.6449966430664
2009-01-01	78.3410034179688
2010-01-01	78.0749969482422
2011-01-01	77.7750015258789
2012-01-01	77.5130004882813
2013-01-01	77.2720031738281
2014-01-01	76.9369964599609
2015-01-01	77.2789993286133
2016-01-01	77.5569992065430
2017-01-01	77.6490020751953