Year	Percent
1998-01-01	35.9411179549759
1999-01-01	36.3610035763855
2000-01-01	36.9533254205001
2001-01-01	37.5932254235855
2002-01-01	38.0420912690716
2003-01-01	38.4230135357230
2004-01-01	39.0028756942398
2005-01-01	38.8498806052659
2006-01-01	39.3396248987576
2007-01-01	39.4388703111638
2008-01-01	39.4439860756421
2009-01-01	38.5342120537905
2010-01-01	38.0878789531318
2011-01-01	38.0705007143766
2012-01-01	37.8398527186309
2013-01-01	36.9556717089726