How interesting. This video estimates the number of Muslims in America to be 9,000,000, but every other reliable source I've found (Pew research, the American Religious Identification Survey by Trinity College, etc.) estimates the number to be much less than half of that.

In fact, there seem to be less estimated Muslims in the US than Jews. And Wiccans, Druids, etc., seem to outclass Muslims in pure numbers.

In the US, at least. I can't speak for European countries.