Year % of total 1990 9.522894232185552 1991 9.658126235747607 1992 9.357070127350706 1993 9.745353432782766 1994 9.719368439306338 1995 10.174632968989753 1996 9.851627519643145 1997 9.343345063106627 1998 8.89950811496381 1999 8.83194183410804 2000 8.974444339604885 2001 9.28767207325605 2002 9.55633627069343 2003 10.857124813876426 2004 9.913814545909169 2005 10.571404059810858 2006 10.451152422735422 2007 9.84139097089714 2008 9.41854009139117 2009 8.704498379970305 2010 10.310134485733984 2011 10.83171010495124 2012 9.778633704867683 2013 10.15799420647493 2014 10.428384040462769 2015 10.450820956396713 2016 10.395330369734728