Year	Percent
1991-01-01	51.2949981689453
1992-01-01	51.6230010986328
1993-01-01	51.3100013732910
1994-01-01	51.2070007324219
1995-01-01	50.9350013732910
1996-01-01	51.4150009155273
1997-01-01	52.5489997863770
1998-01-01	52.5449981689453
1999-01-01	52.9300003051758
2000-01-01	50.5460014343262
2001-01-01	48.8419990539551
2002-01-01	50.5190010070801
2003-01-01	52.4080009460449
2004-01-01	51.0349998474121
2005-01-01	51.5069999694824
2006-01-01	52.0439987182617
2007-01-01	53.2150001525879
2008-01-01	52.6479988098145
2009-01-01	48.8489990234375
2010-01-01	46.8180007934570
2011-01-01	48.9469985961914
2012-01-01	50.3860015869141
2013-01-01	51.4239997863770
2014-01-01	52.7849998474121
2015-01-01	53.8600006103516
2016-01-01	55.7700004577637
2017-01-01	56.2669982910156