Year Number 2004-01-01 11.2885 2005-01-01 14.2677 2006-01-01 15.5485 2007-01-01 16.2991 2008-01-01 16.5749 2009-01-01 19.0850 2010-01-01 26.7454 2011-01-01 30.5399 2012-01-01 32.7954 2013-01-01 24.7109 2014-01-01 28.7330 2015-01-01 28.0110