select multiple objects and drag & drop onto a newly inserted Chart object. Plant Simulation asks you for the Statistic Type. Select Resource Statistic. You get a chart with stacked columns.
Another way to generate a statistic is to select multiple objects and click the right mouse button and select Show Statistics Report.
There is a third possibility: Prepare a frame, how it is described in the Example Collection and drag & drop this frame onto a Chart object. Please look at Catagory Information Flow > Tipic: Statistics of a Frame. You can try multiple different evaluations.