instance method get_confidence

# File actionmailer/lib/action_mailer/vendor/tmail-1.2.7/tmail/vendor/rchardet-1.3/lib/rchardet/sbcharsetprober.rb, line 110
    def get_confidence
      r = 0.01
      if @_mTotalSeqs > 0
        #            print self._mSeqCounters[POSITIVE_CAT], self._mTotalSeqs, self._mModel['mTypicalPositiveRatio']
        r = (1.0 * @_mSeqCounters[POSITIVE_CAT]) / @_mTotalSeqs / @_mModel['mTypicalPositiveRatio']
        #            print r, self._mFreqChar, self._mTotalChar
        r = r * @_mFreqChar / @_mTotalChar
        if r >= 1.0
          r = 0.99
        end
      end
      return r
    end