Year	Percent
1998-01-01	3.99845613195152
1999-01-01	4.35225627031186
2000-01-01	4.04880544119445
2001-01-01	3.90174896928540
2002-01-01	3.66102779828284
2003-01-01	3.37150870466040
2004-01-01	3.60932288841253
2005-01-01	3.38080508158549
2006-01-01	3.09728752409413
2007-01-01	2.84689873184121
2008-01-01	2.78564255911615
2009-01-01	3.77393501420304
2010-01-01	5.39169691883325
2011-01-01	7.94239887408705
2012-01-01	11.14735914721280
2013-01-01	12.59332549385430