Year % of total 2000 100 2001 100 2002 100 2003 100 2004 100 2005 99.12663755458514 2006 99.08256880733946 2007 99.10714285714286 2008 98.68421052631578 2009 98.83268482490273 2010 98.97610921501706 2011 100 2012 100 2013 99.09706546275395 2014 99.09706546275395 2015 99.2467043314501