Year % of total 1990 4.998004844389196 1991 5.120881003263075 1992 5.65431668763903 1993 5.171556200127403 1994 4.790634887153503 1995 5.131323006072084 1996 6.577049262079482 1997 8.084425227588088 1998 6.94563066904143 1999 8.090775418667736 2000 10.762100057034473 2001 6.770281725972754 2002 9.029303346353876 2003 7.572801934866661 2004 7.800969235530926 2005 8.91323825137059 2006 10.977323276831997 2007 7.656968732583722 2008 8.017818465320682 2009 7.676273826233881 2010 8.526638650237961 2011 8.808935178628309 2012 8.675317152066533 2013 9.089542955622724 2014 9.940674787616002 2015 10.38142422154436 2016 9.987233644616362