Year % of total 1990 99.9999999997722 1995 99.9999999997459 2000 100 2005 100 2010 100 2011 100 2012 99.9999999999627 2013 99.8704497249189 2014 99.8344140530631 2015 99.8116826887052 2016 99.5957983323731 2017 99.5981414813269