Year % of total 1990 99.9999999997679 1995 99.9999999997069 2000 100 2005 100 2010 100 2011 100 2012 99.9999999999499 2013 99.9920369789871 2014 99.9028728382935 2015 99.9269958828391 2016 98.9068466969409 2017 98.9402145057529