APEX version is important here, since 5.1 charts do this out of the box.
Providing table structure and desired layout would also go a long way in describing your problem, and forming a solution.
It's APEX version 5.0. It's a pretty straight forward structure. It's has a report date which is just the monthend date, a metric (Channel for example) then a metric name which is the subset of the metric. In this case I would have 3 Channels with a balance associated with each for each monthend. I would like the months to be the label (x axis) and the series would be the metric name charting balances over the months. The basic query would look something like this....
where metric = :P1_METRIC
Hope that helps.