Year	Percent
1991-01-01	40.8419990539551
1992-01-01	40.7830009460449
1993-01-01	40.7739982604980
1994-01-01	40.8479995727539
1995-01-01	40.7719993591309
1996-01-01	40.7330017089844
1997-01-01	40.6090011596680
1998-01-01	40.5069999694824
1999-01-01	40.3959999084473
2000-01-01	40.1800003051758
2001-01-01	40.0849990844727
2002-01-01	39.9959983825684
2003-01-01	39.9249992370605
2004-01-01	39.8829994201660
2005-01-01	39.8680000305176
2006-01-01	39.8779983520508
2007-01-01	39.9430007934570
2008-01-01	40.0419998168945
2009-01-01	40.1430015563965
2010-01-01	40.2589988708496
2011-01-01	40.3829994201660
2012-01-01	40.5169982910156
2013-01-01	40.6529998779297
2014-01-01	40.8050003051758
2015-01-01	40.9669990539551
2016-01-01	41.0929985046387
2017-01-01	41.2239990234375