Year	Percent
1991-01-01	48.3629989624023
1992-01-01	49.0820007324219
1993-01-01	50.2109985351563
1994-01-01	50.7569999694824
1995-01-01	51.2879981994629
1996-01-01	50.3279991149902
1997-01-01	50.9109992980957
1998-01-01	50.0009994506836
1999-01-01	47.7309989929199
2000-01-01	48.1640014648438
2001-01-01	52.2540016174316
2002-01-01	52.6590003967285
2003-01-01	54.3380012512207
2004-01-01	55.4090003967285
2005-01-01	57.3699989318848
2006-01-01	57.5810012817383
2007-01-01	59.3139991760254
2008-01-01	59.9900016784668
2009-01-01	60.1479988098145
2010-01-01	61.4830017089844
2011-01-01	62.6790008544922
2012-01-01	63.7509994506836
2013-01-01	64.0250015258789
2014-01-01	64.3629989624023
2015-01-01	64.7669982910156
2016-01-01	64.3990020751953
2017-01-01	64.1439971923828