Year	Percent
1991-01-01	49.6559982299805
1992-01-01	49.9109992980957
1993-01-01	49.1899986267090
1994-01-01	47.4070014953613
1995-01-01	48.1170005798340
1996-01-01	47.3959999084473
1997-01-01	51.0050010681152
1998-01-01	50.3230018615723
1999-01-01	49.5999984741211
2000-01-01	48.0880012512207
2001-01-01	48.5489997863770
2002-01-01	49.8050003051758
2003-01-01	50.0929985046387
2004-01-01	50.5489997863770
2005-01-01	51.5180015563965
2006-01-01	54.8580017089844
2007-01-01	56.5600013732910
2008-01-01	56.7330017089844
2009-01-01	49.5699996948242
2010-01-01	47.4939994812012
2011-01-01	49.1419982910156
2012-01-01	50.8230018615723
2013-01-01	52.4010009765625
2014-01-01	52.9350013732910
2015-01-01	54.2970008850098
2016-01-01	54.8769989013672
2017-01-01	55.3419990539551