Year	Number
2004-01-01	2.5605
2005-01-01	2.4373
2006-01-01	2.3720
2007-01-01	2.3746
2008-01-01	2.3809
2009-01-01	2.5094
2010-01-01	2.9392
2011-01-01	3.0357
2012-01-01	3.0726
2013-01-01	3.1772
2014-01-01	3.2394
2015-01-01	3.3608