Year % of total 1990 23.83031156486534 1991 21.421516874978717 1992 6.798576665947811 1993 1.9018228792880725 1994 3.3931317273193233 1995 1.6863905325443789 1996 4.033002893910473 1997 3.37086460939672 1998 1.6207077479158165 1999 7.63236305294522 2000 14.53106735005845 2001 13.11795014621919 2002 12.194980918237539 2003 13.373698746547694 2004 14.350469283276452 2005 20.929587235518557 2006 20.402417818994785 2007 17.85449146250928 2008 15.202221055001125 2009 14.34815270094926 2010 63.79655586704045 2011 62.835609985869056 2012 63.56811658202693 2013 52.65780730897009 2014 47.16828478964401 2015 46.477219351808365