Year	Percent
1991-01-01	12.5500001907349
1992-01-01	13.2449998855591
1993-01-01	13.9099998474121
1994-01-01	14.1470003128052
1995-01-01	13.6379995346069
1996-01-01	13.8590002059937
1997-01-01	14.1409997940063
1998-01-01	14.0089998245239
1999-01-01	14.9519996643066
2000-01-01	19.1819992065430
2001-01-01	23.3330001831055
2002-01-01	28.3209991455078
2003-01-01	19.2719993591309
2004-01-01	20.0410003662109
2005-01-01	19.3190002441406
2006-01-01	17.5370006561279
2007-01-01	18.7000007629395
2008-01-01	22.9290008544922
2009-01-01	16.1639995574951
2010-01-01	20.0960006713867
2011-01-01	35.6349983215332
2012-01-01	35.6529998779297
2013-01-01	35.5270004272461
2014-01-01	34.9360008239746
2015-01-01	35.1860008239746
2016-01-01	35.1170005798340
2017-01-01	35.1290016174316