Year	Percent
1991-01-01	7.14799976348877
1992-01-01	7.38999986648560
1993-01-01	7.42899990081787
1994-01-01	7.11100006103516
1995-01-01	7.46999979019165
1996-01-01	7.26499986648560
1997-01-01	6.11800003051758
1998-01-01	4.97900009155273
1999-01-01	2.95799994468689
2000-01-01	2.80100011825562
2001-01-01	2.73600006103516
2002-01-01	2.80200004577637
2003-01-01	2.61299991607666
2004-01-01	2.50000000000000
2005-01-01	2.44899988174438
2006-01-01	2.36999988555908
2007-01-01	2.28399991989136
2008-01-01	2.22499990463257
2009-01-01	2.89599990844727
2010-01-01	3.50500011444092
2011-01-01	4.19799995422363
2012-01-01	4.75500011444092
2013-01-01	5.43699979782104
2014-01-01	4.95399999618530
2015-01-01	5.12799978256226
2016-01-01	4.98899984359741
2017-01-01	4.30600023269653