legend label for subplots

In my figure I have 6 subplots, each displaying the same set of conditions - so I only really need one legend label for all of them. Is there a solution to this?

Answer 1

[Image Analyst]

Can't you just put the legend in one and then users can/will assume the legend applies to all the other 5 plots? Or else put up a text saying so, if you don't think they will assume that.