Year % of total 1990 99 1995 99 1997 99 1998 99 1999 99 2000 99 2001 99 2002 99 2003 99 2004 98 2005 98.7 2006 99 2007 98.4 2008 98.5 2009 98.9 2010 99.1 2011 99.1 2012 98.9 2013 98.6 2014 98.9 2015 98 2016 99 2018 99 2019 99