Year Number 2003 27.54296 2004 28.8882 2005 28.66179 2006 27.86807 2007 27.26688 2008 26.74344 2009 23.99372 2010 25.13398 2011 24.72253 2012 25.70554 2013 23.4811 2014 23.22809 2015 22.98212 2016 23.0195