Year	Percent
1991-01-01	53.3300018310547
1992-01-01	53.6310005187988
1993-01-01	53.8489990234375
1994-01-01	53.9399986267090
1995-01-01	53.9780006408691
1996-01-01	53.8199996948242
1997-01-01	53.0229988098145
1998-01-01	52.7239990234375
1999-01-01	52.4980010986328
2000-01-01	52.1370010375977
2001-01-01	52.2140007019043
2002-01-01	52.2659988403320
2003-01-01	52.7770004272461
2004-01-01	52.8549995422363
2005-01-01	52.9329986572266
2006-01-01	53.0159988403320
2007-01-01	53.0919990539551
2008-01-01	53.6609992980957
2009-01-01	54.2109985351563
2010-01-01	55.1279983520508
2011-01-01	55.0629997253418
2012-01-01	54.9529991149902
2013-01-01	54.7840003967285
2014-01-01	54.6739997863770
2015-01-01	54.5579986572266
2016-01-01	54.4160003662109
2017-01-01	54.3419990539551