I am displaying a chart where the peformance line matches the goal line for
several months in a row. The data line is hidden underneath the goal line,
so it looks like the data is missing - (even though it matched the goal). Is
there a way to pry the peformance data line out from under the goal line,
that is, to superimpose the data line over the goal line in such a way that
both lines are still visible?