Year	Number
2004-01-01	2.5308
2005-01-01	2.6751
2006-01-01	2.7399
2007-01-01	2.9056
2008-01-01	3.1102
2009-01-01	3.4845
2010-01-01	3.8579
2011-01-01	4.1441
2012-01-01	4.3396
2013-01-01	4.5198