Year	Percent
1991-01-01	12.6269998550415
1992-01-01	14.7989997863770
1993-01-01	23.6840000152588
1994-01-01	27.5890007019043
1995-01-01	44.2919998168945
1996-01-01	40.2309989929199
1997-01-01	34.7360000610352
1998-01-01	29.5680007934570
1999-01-01	32.9029998779297
2000-01-01	35.2159996032715
2001-01-01	40.8790016174316
2002-01-01	46.5550003051758
2003-01-01	36.6080017089844
2004-01-01	29.3199996948242
2005-01-01	26.0300006866455
2006-01-01	23.6599998474121
2007-01-01	20.7059993743896
2008-01-01	18.8400001525879
2009-01-01	21.1700000762939
2010-01-01	19.3600006103516
2011-01-01	18.7299995422363
2012-01-01	18.2800006866455
2013-01-01	19.4300003051758
2014-01-01	18.8400001525879
2015-01-01	20.0729999542236
2016-01-01	23.5279998779297
2017-01-01	23.4909992218018