Year	Percent
1986-01-01	60.0309949517213
1987-01-01	60.8152612405674
1988-01-01	59.3085408063329
1989-01-01	57.2669006665779
1990-01-01	58.2735985247383
1991-01-01	57.2022593164888
1992-01-01	57.0954038448559
1993-01-01	57.5973246675490
1994-01-01	59.4646712315475
1995-01-01	61.3074033214960
1996-01-01	62.8596975681377
1997-01-01	62.3108998144279
1998-01-01	61.6262551529993
1999-01-01	62.5141326995591
2000-01-01	63.1158099536553
2001-01-01	64.4306324273654
2002-01-01	65.0012944251813
2003-01-01	65.3977847727336
2004-01-01	66.0149436888408
2005-01-01	67.4223916837995
2006-01-01	67.9618360554868
2007-01-01	68.6087993948985
2008-01-01	68.5850677375314
2009-01-01	67.2692364808878
2010-01-01	66.5275343459949
2011-01-01	67.0967465546972
2012-01-01	66.8289717559709
2013-01-01	67.7364958324036
2014-01-01	69.0623239449313
2015-01-01	69.1918374274455
2016-01-01	70.6432669636405
2017-01-01	72.0344264482842