We shall now insert a Chart to view the number of parts that occupy the buffer as the simulation is running.
Reset the simulation in the EventController.
Click the Chart
on
the tab User Interface in the Toolbox.
Insert the object Chart above the Buffer.
Drag and drop the Buffer on the Chart. The Chart window opens as a histogram.
Click Reset and Start in the EventController.

The Histogram shows how many percent of time how many parts were located in the buffer. So in the diagram below, about 21% of the time, there were 0 parts (no part) located in the buffer, about 12% of the time, there was 1 part located in the buffer etc.

To reopen the chart display window (in case you closed the window), right-click the Chart object and select Show Display Window.