Year % of total 1990 17.4082906087933 1995 0.0518357813769632 2000 0.0504999349027924 2005 0.17602926478304 2010 11.8831308543839 2011 16.0075155239148 2012 0.0892749635345358 2013 0.088564082329179 2014 0.169311430789154 2015 0.173717183196898 2016 0.172066740700039 2017 0.170271457079296