Year	Percent
1991-01-01	59.1850013732910
1992-01-01	59.8950004577637
1993-01-01	60.3460006713867
1994-01-01	60.8209991455078
1995-01-01	60.8209991455078
1996-01-01	59.6440010070801
1997-01-01	59.4420013427734
1998-01-01	59.4249992370605
1999-01-01	59.3590011596680
2000-01-01	59.4300003051758
2001-01-01	59.2490005493164
2002-01-01	56.2900009155273
2003-01-01	57.6479988098145
2004-01-01	58.2470016479492
2005-01-01	59.5880012512207
2006-01-01	60.2509994506836
2007-01-01	59.8240013122559
2008-01-01	59.2270011901855
2009-01-01	58.4739990234375
2010-01-01	58.5449981689453
2011-01-01	59.0330009460449
2012-01-01	58.5410003662109
2013-01-01	57.3100013732910
2014-01-01	57.3740005493164
2015-01-01	57.6930007934570
2016-01-01	57.1749992370605
2017-01-01	57.1539993286133