Year % of total 1995 100 1998 98 1999 99.3 2000 100 2001 100 2002 100 2004 100 2005 100 2007 100 2008 99.2 2009 98.9 2010 98.3 2011 98.8 2012 99.2 2013 99 2014 99.9 2015 98.7 2016 98.6