The filledAccumulative Line chart setting
This page shows how the setting
affects your charts. The first chart shown below has
it enabled (the default), so the lines, in effect, sit on top of
each other. The second chart has the setting
set to false so the points are drawn "as-is", ie not
accumulatively. The first chart could be more useful if you
wish to see totals, whereas the second chart below
might be better if you want to see individual values.
Keep in mind that if you choose to use a non-accumulative chart the colors may be better as semi-transparent ones, otherwise parts or all of some lines may get hidden by others.