Year % of total 1990 68.5871453387377 1991 55.695670449768805 1992 43.31408262994225 1993 8.673550436854645 1994 11.240721102863201 1995 7.64251033986693 1996 2.043772127454136 1997 0.3151434732128048 1998 0 1999 0 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