Year	Percent
1991-01-01	13.8800001144409
1992-01-01	15.6800003051758
1993-01-01	17.4799995422363
1994-01-01	16.3600006103516
1995-01-01	15.5500001907349
1996-01-01	14.9399995803833
1997-01-01	13.6000003814697
1998-01-01	12.4600000381470
1999-01-01	12.4200000762939
2000-01-01	12.0299997329712
2001-01-01	10.3299999237061
2002-01-01	10.9200000762939
2003-01-01	11.3599996566772
2004-01-01	10.7200002670288
2005-01-01	12.7399997711182
2006-01-01	13.9300003051758
2007-01-01	14.2799997329712
2008-01-01	15.0200004577637
2009-01-01	19.1200008392334
2010-01-01	19.8799991607666
2011-01-01	21.2900009155273
2012-01-01	21.2099990844727
2013-01-01	20.6800003051758
2014-01-01	16.9599990844727
2015-01-01	14.6300001144409
2016-01-01	12.9899997711182
2017-01-01	12.0799999237061