Year	Number
2004-01-01	1.7979
2005-01-01	2.0191
2006-01-01	2.0512
2007-01-01	2.3771
2008-01-01	2.5116
2009-01-01	2.8698
2010-01-01	3.2867
2011-01-01	3.5085
2012-01-01	3.7262
2013-01-01	3.7374
2014-01-01	3.9705
2015-01-01	4.1237
2016-01-01	4.1954
2017-01-01	4.2774