Year	Number
2004-01-01	3.7093
2005-01-01	3.7187
2006-01-01	3.8296
2007-01-01	4.1176
2008-01-01	4.3514
2009-01-01	4.4725
2010-01-01	4.5012
2011-01-01	4.5117
2012-01-01	4.4729
2013-01-01	4.4749
2014-01-01	4.4813
2015-01-01	4.5341