Year	Percent
1998-01-01	17.2169267175723
1999-01-01	18.2702604653350
2000-01-01	17.2287379691846
2001-01-01	16.2508494428577
2002-01-01	15.7467758181965
2003-01-01	15.1178789779987
2004-01-01	16.3057627541957
2005-01-01	15.4323627964316
2006-01-01	13.7607214892080
2007-01-01	12.9075324053316
2008-01-01	11.5141594088481
2009-01-01	13.2809161851809
2010-01-01	16.3363847384762
2011-01-01	21.5093755786366
2012-01-01	28.2093309698227
2013-01-01	31.3487777349081
2014-01-01	30.1669958748271
2015-01-01	28.8586434967893
2016-01-01	28.0976867976655
2017-01-01	26.0708246868340