Actually, you could do several things.
(BTW, I have a Dutch version of Excel 2000, so the names of options might be a bit off.)
1. Easiest is to right click on the upper axis (when the mouse hovers over the axis, you'll see the popup hint 'Category axis': then you do the right click). Select the option Format axis and open the tab Patterns. Select by Tick(?) labels(!) the option High, and click OK.
2. Almost as easy: Open the same dialog for the left axis (Value axis), open the tab Scale and check 'Category axis crosses? at:' and enter -110 (the lowest value in your graph). Click OK.
Regards,
Karel