Year	Percent
1997-01-01	2.586957693
1998-01-01	3.088430166
1999-01-01	2.374129057
2000-01-01	1.856835246
2001-01-01	2.517348051
2002-01-01	4.095108509
2003-01-01	5.234840870
2004-01-01	4.987242699
2005-01-01	3.870083332
2006-01-01	2.895938158
2007-01-01	2.263943434
2008-01-01	1.785920143
2009-01-01	2.098743439
2010-01-01	2.317393541
2011-01-01	2.713223696
2012-01-01	4.754991055
2013-01-01	7.485084057