You can either set the "Horizontal axis crosses: Axis value" property in the Y-axis which would move the axis but have the unfortunate side effect of causing all bars to "rise" from the minimum value, or you can set the "Label distance from axis" property in the X-axis, which will keep the axis where it should be, at Y = 0, but move the labels to below the chart.
I can't see anything else but I'm happy to be proved wrong
