Year	Percent
1991-01-01	52.7799987792969
1992-01-01	54.0589981079102
1993-01-01	53.8479995727539
1994-01-01	53.9690017700195
1995-01-01	54.2529983520508
1996-01-01	55.1949996948242
1997-01-01	56.9249992370605
1998-01-01	58.3180007934570
1999-01-01	59.5369987487793
2000-01-01	61.1220016479492
2001-01-01	62.1220016479492
2002-01-01	62.4529991149902
2003-01-01	61.7820014953613
2004-01-01	61.2840003967285
2005-01-01	61.3250007629395
2006-01-01	62.1800003051758
2007-01-01	63.4739990234375
2008-01-01	64.3369979858398
2009-01-01	64.1009979248047
2010-01-01	61.8139991760254
2011-01-01	60.9360008239746
2012-01-01	60.8349990844727
2013-01-01	59.8310012817383
2014-01-01	59.2639999389648
2015-01-01	59.6679992675781
2016-01-01	59.8839988708496
2017-01-01	60.4430007934570