Year % 1977 75.54348 1978 70.2381 1993 89.50749 1997 97.23305 1998 94.27224 1999 93.94585 2000 94.74282 2005 97.61769 2008 100 2009 99.54822 2010 100 2011 100 2012 96.9166 2013 100 2016 100