Year	Number
2004-01-01	17.6137
2005-01-01	19.2768
2006-01-01	21.4558
2007-01-01	24.4208
2008-01-01	28.5241
2009-01-01	31.1214
2010-01-01	35.8666
2011-01-01	41.1392
2012-01-01	45.0983
2013-01-01	52.1186
2014-01-01	56.7390
2015-01-01	60.0548
2016-01-01	60.2536
2017-01-01	61.5075