Year % of total 1990 2.60755095441558 1995 2.60807124205589 2000 1.35137030335008 2005 1.32210336435618 2010 0 2011 0 2012 0 2013 0 2014 0 2015 1.26391262649848 2016 1.25801896240424 2017 1.25213209118987