Year % of total 1990 55.3943883512523 1995 57.0007146654744 2000 43.485858312646 2005 37.1434287353243 2010 25.3203394310416 2011 40.0145631663992 2012 15.5356142687961 2013 0 2014 0 2015 0 2016 0 2017 0