function getPercentageAxis() {
            const uniqueDataPoints = new Set(data.map(getValue));
            const allZeroes = uniqueDataPoints.size === 1 && uniqueDataPoints.has(0);
            if (allZeroes) {
                return percentageAxisToMaxRatio;
            }

            return Math.min(percentageAxisToMaxRatio * d3Array.max(data, getValue));
        }
Gets the percentageAxis, sets it to `percentageAxisToMaxRatio` if all data points are 0
@return {number} Calculated percentageAxis
@private