Year	Percent
1991-01-01	4.54699993133545
1992-01-01	4.63899993896484
1993-01-01	4.51100015640259
1994-01-01	4.59100008010864
1995-01-01	4.62200021743774
1996-01-01	4.45800018310547
1997-01-01	4.40700006484985
1998-01-01	4.44600009918213
1999-01-01	4.40700006484985
2000-01-01	4.32399988174438
2001-01-01	4.34399986267090
2002-01-01	4.36800003051758
2003-01-01	4.53999996185303
2004-01-01	4.56500005722046
2005-01-01	4.61100006103516
2006-01-01	4.47200012207031
2007-01-01	4.51399993896484
2008-01-01	4.52099990844727
2009-01-01	4.31899976730347
2010-01-01	4.50899982452393
2011-01-01	4.57800006866455
2012-01-01	4.45300006866455
2013-01-01	4.42299985885620
2014-01-01	4.40899991989136
2015-01-01	4.41400003433228
2016-01-01	4.39099979400635
2017-01-01	4.37200021743774