Year	Percent
1991-01-01	45.7550010681152
1992-01-01	46.0979995727539
1993-01-01	46.0009994506836
1994-01-01	47.5359992980957
1995-01-01	46.9319992065430
1996-01-01	45.7130012512207
1997-01-01	45.4199981689453
1998-01-01	45.4659996032715
1999-01-01	45.4000015258789
2000-01-01	46.5670013427734
2001-01-01	46.8600006103516
2002-01-01	46.7890014648438
2003-01-01	46.0060005187988
2004-01-01	45.7589988708496
2005-01-01	44.9510002136230
2006-01-01	43.6230010986328
2007-01-01	43.4029998779297
2008-01-01	42.5680007934570
2009-01-01	40.1650009155273
2010-01-01	38.8720016479492
2011-01-01	39.4869995117188
2012-01-01	38.4770011901855
2013-01-01	39.3559989929199
2014-01-01	39.7050018310547
2015-01-01	42.4749984741211
2016-01-01	41.0069999694824
2017-01-01	40.5579986572266