Year % of total 1990 33.9995805658833 1995 24.289509636329 2000 18.4046341040711 2005 19.0254147439945 2010 13.4589879659774 2011 28.7135904678379 2012 13.918119054491 2013 5.38236338344817 2014 3.51733021602346 2015 4.41205598574357 2016 0 2017 0.235993227759768