Year % of total 1990 33.6213311226157 1995 33.7586340017717 2000 11.6607607435924 2005 13.35929632477 2010 15.1565554804827 2011 15.4983338203787 2012 15.8457474277768 2013 16.2108450773339 2014 16.5989802462163 2015 17.0064417974656 2016 0 2017 0