Year % of total 1989 98 1998 99.7 2000 99.7 2001 99.9 2011 99.9 2012 99.9 2013 99.9 2014 99.9 2015 99.9 2016 99.9 2017 99.9 2018 99.9 2019 99.9 2020 98.6