Year % of total 1972 100 1975 100 1976 100 1977 99.999604109345 1978 100 1979 99.99964834051892 1980 100 1981 100 1984 99.99975708462686 1985 100 1986 100 1988 100 1989 100 1990 100 1991 99.99999999999997 1992 100 1995 100 1996 100 1997 100 1998 99.9998552304514 1999 100 2002 99.9674076094368 2003 99.96233325501234 2004 99.95104033263631 2005 99.94039644876365 2006 99.92246629204043 2007 99.91016083263122 2008 99.89146247147602 2009 99.88027152157939 2010 99.67246958175133 2011 99.23845357507422 2012 99.03840897287546 2013 98.75759658797983 2014 97.78846166266452