Year Number 2004-01-01 16.2303 2005-01-01 11.3296 2006-01-01 13.4767 2007-01-01 18.4247 2008-01-01 21.7471 2009-01-01 23.6397 2010-01-01 26.2251 2011-01-01 30.4380 2012-01-01 35.0148 2013-01-01 41.0865 2014-01-01 50.5401 2015-01-01 50.1756 2016-01-01 59.4203