Year	Percent
1997-01-01	20.8971
1998-01-01	20.9190
1999-01-01	23.8346
2000-01-01	24.8431
2001-01-01	28.4338
2002-01-01	20.7581
2003-01-01	15.6644
2004-01-01	18.2357
2005-01-01	22.9001
2006-01-01	26.0816
2007-01-01	28.7475
2008-01-01	34.4676
2009-01-01	40.5967
2010-01-01	44.7063
2011-01-01	47.2714
2012-01-01	47.3737
2013-01-01	45.0038
2014-01-01	43.6897
2015-01-01	42.9397