Year % of total 1990 98.9095360164241 1995 96.8574803978865 2000 100 2005 98.9783095740322 2010 99.8908780725016 2011 100 2012 100 2013 97.1393921126607 2014 99.89114417748 2015 100 2016 100 2017 100