Year	Percent
1991-01-01	56.3799536500583
1992-01-01	55.9403886764419
1993-01-01	55.3443871371040
1994-01-01	55.4312514919093
1995-01-01	55.4876321700463
1996-01-01	55.6353916590187
1997-01-01	55.9730070797536
1998-01-01	56.0139650434887
1999-01-01	56.1506812505485
2000-01-01	56.3057462856748
2001-01-01	56.0773232054506
2002-01-01	55.7310799314406
2003-01-01	55.5151244937247
2004-01-01	55.5597200108990
2005-01-01	55.9097974403210
2006-01-01	56.3467936536086
2007-01-01	56.6971163875528
2008-01-01	56.5985739236342
2009-01-01	55.0974081685735
2010-01-01	54.8137380850197
2011-01-01	54.9198478784817
2012-01-01	55.0112234415615
2013-01-01	55.0229414266414
2014-01-01	55.2909536356723
2015-01-01	55.6677646010552
2016-01-01	56.0979665680569
2017-01-01	56.2690935997223