Create a custom chart, two stacked bars/month w/ two axes?

[Oscar]

I would like to compare two data sets on the same chart using stacked bars.
The data ranges are different by several orders of magnitude in one case, so
I would like to use two axes. My x-axis is time in months. I would like to
have both data sets displayed against each month. I cannot find a
appropriate chart in PowerPoint's custom chart nor can I find instructions on
how to create a custom chart. Anyone have an idea? Maybe Excel is the way
to go.

 

[John Mansfield]

Oscar,

Perhaps these examples can help:

http://www.peltiertech.com/Excel/Charts/ColumnsOnTwoAxes.html

http://www.pdbook.com/index.php/excel/two_column_series_with_two_axes/