Year	Percent
1991-01-01	56.6599998474121
1992-01-01	56.7849998474121
1993-01-01	56.4000015258789
1994-01-01	56.3069992065430
1995-01-01	56.3940010070801
1996-01-01	55.9249992370605
1997-01-01	55.2459983825684
1998-01-01	54.4850006103516
1999-01-01	53.7010002136230
2000-01-01	53.0740013122559
2001-01-01	52.6209983825684
2002-01-01	52.2150001525879
2003-01-01	52.0789985656738
2004-01-01	53.8289985656738
2005-01-01	53.5690002441406
2006-01-01	51.9519996643066
2007-01-01	50.3530006408691
2008-01-01	50.6749992370605
2009-01-01	51.2980003356934
2010-01-01	51.6860008239746
2011-01-01	52.1180000305176
2012-01-01	52.6049995422363
2013-01-01	53.8810005187988
2014-01-01	55.1180000305176
2015-01-01	54.9230003356934
2016-01-01	54.7220001220703
2017-01-01	54.5730018615723