It isn't clear where the whitespace is (between the bars or on top of
them).

If the former, double-click the axis and in the Options tab experiment
with Gap Width. Alternatively, change the axis type from Time to
Category (select the chart then Chart | Chart Options... | Axis tab)

If the latter, double-click the y-axis and from the Scale tab adjust the
min./max. values.

In article . com,
says...
I have a bar chart that has a significant amount of whitespace in the
chart area that I can't seem to get the chart to fill up. I have tried
extending the area to fit the plot area, but that only made it bigger.
Does anyone know who to get their charts to actually fill up the plot
area?