Anecdotal evidence, number of festivals, homilies on the subject...
I suppose it could be researched, then, but doubt that it has. (Odd thought: I read somewhere that at the time of the Russian Revolution, 101 years ago, there were -— could it be? -— 20,000 churches, shrines, monasteries and convents in Russia named in honor of Mary. It seems high, but that’s the way I remember it.) Why do you ask?