Year	Percent
1991-01-01	24.9810009002686
1992-01-01	21.7129993438721
1993-01-01	21.5009994506836
1994-01-01	24.3549995422363
1995-01-01	23.5079994201660
1996-01-01	29.5909996032715
1997-01-01	32.1710014343262
1998-01-01	32.0359992980957
1999-01-01	24.2399997711182
2000-01-01	20.8649997711182
2001-01-01	19.8689994812012
2002-01-01	27.4890003204346
2003-01-01	24.5209999084473
2004-01-01	27.8320007324219
2005-01-01	27.9790000915527
2006-01-01	29.4589996337891
2007-01-01	30.7369995117188
2008-01-01	35.1710014343262
2009-01-01	38.0509986877441
2010-01-01	35.7680015563965
2011-01-01	35.1100006103516
2012-01-01	32.9150009155273
2013-01-01	35.5120010375977
2014-01-01	30.4979991912842
2015-01-01	30.3320007324219
2016-01-01	29.9319992065430
2017-01-01	28.7759990692139