Year	Percent
1986-01-01	66.9148453751796
1987-01-01	64.2518618821936
1988-01-01	60.1349771483670
1989-01-01	56.5371847596809
1990-01-01	56.6143295362981
1991-01-01	56.4564761865028
1992-01-01	56.4081641800578
1993-01-01	59.4369980847554
1994-01-01	62.5087357573113
1995-01-01	65.0358798816671
1996-01-01	68.6435126857511
1997-01-01	69.1139067603955
1998-01-01	70.3083640942031
1999-01-01	71.2684779174460
2000-01-01	71.8645353927402
2001-01-01	73.7688305189709
2002-01-01	77.0515136014782
2003-01-01	75.9722234921104
2004-01-01	78.0157429819910
2005-01-01	79.5196511742547
2006-01-01	81.0983887560539
2007-01-01	81.8955662156371
2008-01-01	81.6813066075712
2009-01-01	82.5600342038565
2010-01-01	82.5028297458744
2011-01-01	82.5706558646600
2012-01-01	82.8352247256276
2013-01-01	82.2769642521056
2014-01-01	83.3463267826194
2015-01-01	83.1956938912366
2016-01-01	84.3246994571417
2017-01-01	86.8600488549926