def gap_width(self):
        """
        Width of gap between bar(s) of each category, as an integer
        percentage of the bar width. The default value for a new bar chart is
        150, representing 150% or 1.5 times the width of a single bar.
        """
        gapWidth = self._element.gapWidth
        if gapWidth is None:
            return 150
        return gapWidth.val