Year	Percent
1991-01-01	56.2690010070801
1992-01-01	54.6450004577637
1993-01-01	52.9099998474121
1994-01-01	52.0550003051758
1995-01-01	51.4099998474121
1996-01-01	50.8619995117188
1997-01-01	51.9169998168945
1998-01-01	51.3559989929199
1999-01-01	52.7010002136230
2000-01-01	54.3549995422363
2001-01-01	56.0089988708496
2002-01-01	55.9389991760254
2003-01-01	56.3260002136230
2004-01-01	56.6990013122559
2005-01-01	56.8860015869141
2006-01-01	58.5769996643066
2007-01-01	59.7659988403320
2008-01-01	60.5730018615723
2009-01-01	59.9949989318848
2010-01-01	59.5099983215332
2011-01-01	59.2340011596680
2012-01-01	58.9350013732910
2013-01-01	60.0480003356934
2014-01-01	59.4440002441406
2015-01-01	59.8079986572266
2016-01-01	61.5120010375977
2017-01-01	60.8160018920898