Year % of total 1990 30.750262006041552 1991 30.482456140350877 1992 29.98610682309355 1993 34.108727492030674 1994 37.96267004112623 1995 25.088524590163935 1996 18.503401360544217 1997 7.564718648271586 1998 7.751937984496124 1999 3.4408602150537635 2000 2.9432750624331074 2001 1.986312802537139 2002 2.105989987916451 2003 3.115056104505108 2004 0 2005 0 2006 0 2007 0 2008 0 2009 0 2010 0 2011 0 2012 0 2013 0 2014 0 2015 0