Year	Number
2004-01-01	18.3770
2005-01-01	19.8396
2006-01-01	21.6561
2007-01-01	23.5905
2008-01-01	24.0151
2009-01-01	23.7320
2010-01-01	23.6377
2011-01-01	23.2838
2012-01-01	22.0335
2013-01-01	20.8540
2014-01-01	20.0047
2015-01-01	18.8960
2016-01-01	18.2118