Year Number 2000 8.73943 2001 9.02407 2002 8.28238 2003 8.05055 2004 6.19823 2006 6.07268 2007 6.92747 2008 6.5231 2009 6.3889 2010 6.83465 2011 6.97698 2012 7.30194 2013 9.18652 2014 10.11023 2015 10.16077 2016 9.79702 2017 9.49111