Year % of total 1990 4.791238877481177 1991 4.697986577181208 1992 0.03034210725934916 1993 0.03956635277360133 1994 0.038109756097560975 1995 0.04081632653061225 1996 0.04950495049504951 1997 0.05264266161297116 1998 0.0637213254035684 1999 0.0564334085778781 2000 0 2001 0 2002 0 2003 0 2004 0 2005 0 2006 0 2007 0 2008 0 2009 0 2010 0 2011 0 2012 0 2013 0 2014 0 2015 0