search for: mlegend

Dear Users, I already posted this question: it either went unnoticed, or it is to basic (if this is so, please sent me a hint). I would like to know if there is a way to add a common legend to an arrangement of plots. In the example below, I get four plots in my device. each one has a density for 1995 and one for 2006. I have found that using legend or smartlegend I can add a legend to each plot,