AT LEAST a million.
From what I read many of the 17th-19th century composers were Catholic and they ALL did an "Ave Maria."
Can there be too many songs for the Mother of God?
I don't think so.
And that doesn't count all the settings of the Magnificat, the Four Marian Antiphons, and Masses based on all of them.
Can't be enough of them for the Blessed Virgin. Fortunately in Eternity we will have plenty of time to run them ALL.