Year	Percent
1991-01-01	51.2340011596680
1992-01-01	51.1959991455078
1993-01-01	53.1389999389648
1994-01-01	55.5209999084473
1995-01-01	56.4160003662109
1996-01-01	55.9729995727539
1997-01-01	54.7690010070801
1998-01-01	53.8800010681152
1999-01-01	53.9360008239746
2000-01-01	54.4199981689453
2001-01-01	53.9720001220703
2002-01-01	52.6699981689453
2003-01-01	52.5719985961914
2004-01-01	53.3100013732910
2005-01-01	54.7150001525879
2006-01-01	55.4920005798340
2007-01-01	56.8170013427734
2008-01-01	57.9199981689453
2009-01-01	56.7680015563965
2010-01-01	57.6860008239746
2011-01-01	58.3750000000000
2012-01-01	59.1959991455078
2013-01-01	59.7719993591309
2014-01-01	60.3750000000000
2015-01-01	60.7639999389648
2016-01-01	61.1440010070801
2017-01-01	61.4399986267090