Year	Number
2004-01-01	21.7815
2005-01-01	21.7050
2006-01-01	21.6498
2007-01-01	21.6062
2008-01-01	21.5685
2009-01-01	21.5216
2010-01-01	21.4580
2011-01-01	21.3748
2012-01-01	21.2781
2013-01-01	21.1735
2014-01-01	19.3082
2015-01-01	19.2069
2016-01-01	17.3703
2017-01-01	15.6333