How to set the chart height dynamically.

[ramkumar_cpt]

I have a bar chart. It has maxmimum 4 bars. some time it has 3 or 2 or
1. Actually my problem is if the chart has 4 bars then it looks fine.
if 1 bar show very big size. How to set the same size even if 1 or 4. I
tried to adjust the chart height. My 4 bar chart height is 2.48. So i
will put the one bar chart height is 2.48/4. But bar displayed small
size compare 4 values bar.

Please help me.

Ram