Year % of total 1991 48.33875199373547 1992 48.62996479108715 1993 49.76117801414031 1994 49.3216174335272 1995 49.107485572474936 1996 49.38081858484719 1997 49.50429037316516 1998 49.89942626174969 1999 49.240684597907666 2000 47.825783076318125 2001 48.75642871360706 2002 48.14690002354643 2003 47.08889462143383 2004 46.67831586562215 2005 46.35014657968744 2006 46.11252313463052 2007 44.80999298148365 2008 45.61868485161875 2009 46.729904324308336 2010 44.551619951940694 2011 44.471525010276274 2012 42.87778693596671 2013 43.22285150473401 2014 45.056668987886404 2015 42.070055738001116 2016 42.38929379990612