Year % of total 1985 97.11889567703037 1986 97.49615123864459 1987 97.66756507853358 1988 97.7997028668512 1989 97.47992971706715 1990 97.17144605808033 1991 97.79786587747012 1992 97.34990494845898 1993 96.81020805134503 1994 96.25402969647521 1995 95.71534596516229 1996 94.90562230594904 1997 94.98001559889782 1998 95.00062695756901 1999 95.63205482992649 2000 93.92703293181806 2001 93.11310303986549 2002 92.99211139726543 2003 92.78071901765668 2004 92.9924886972833 2005 93.91377500179435 2006 94.50670300363927 2007 94.49723448647326 2008 94.52912193055741 2009 94.8069340078863 2010 94.84840752311023 2011 95.25304607415367 2012 90.171634027601 2013 92.69368408223224 2014 93.1993828259583