def _ratio(self, key):
total = float(self._total_votes())<EOL>try:<EOL><INDENT>return math.floor(self[key] / total * <NUM_LIT:100>)<EOL><DEDENT>except ZeroDivisionError:<EOL><INDENT>return float(<NUM_LIT:0>)<EOL><DEDENT>
Return the yes/total ratio as a percetage string
        suitable for use as as css attribute.