This history of "Ms." as described in this article in The New York Times is what I'm familiar with:
I noticed the last time I was there that Fräulein was used rarely, when it was more common in the '70's when I first went. It sounds as antiquated as "Master," the formal address used for a boy.
At least in Germany, 'Fräulein' for unmarried women is nowadays only used very, very rarely. It has a rather antiquated connotation.