Year	Number
2004-01-01	2.8462
2005-01-01	3.0104
2006-01-01	3.3388
2007-01-01	3.6125
2008-01-01	3.7767
2009-01-01	3.7219
2010-01-01	3.7219
2011-01-01	3.6672
2012-01-01	3.5577
2013-01-01	3.7767
2014-01-01	4.2146
2015-01-01	4.2693
2016-01-01	4.1598
2017-01-01	4.1051