Year	Percent
1991-01-01	50.0709991455078
1992-01-01	49.3310012817383
1993-01-01	48.9690017700195
1994-01-01	48.8520011901855
1995-01-01	48.9589996337891
1996-01-01	48.0709991455078
1997-01-01	47.2000007629395
1998-01-01	46.4819984436035
1999-01-01	46.4080009460449
2000-01-01	45.4249992370605
2001-01-01	44.1590003967285
2002-01-01	43.8069992065430
2003-01-01	43.9990005493164
2004-01-01	43.1539993286133
2005-01-01	42.3409996032715
2006-01-01	41.8819999694824
2007-01-01	40.8050003051758
2008-01-01	39.7620010375977
2009-01-01	39.4790000915527
2010-01-01	39.3499984741211
2011-01-01	36.5800018310547
2012-01-01	36.4630012512207
2013-01-01	36.2630004882813
2014-01-01	35.9980010986328
2015-01-01	35.4659996032715
2016-01-01	35.3300018310547
2017-01-01	34.9480018615723