A: Not very many.
Did you know that it is against the law in many (most?) Islamic countries to leave Islam. It is punishable by death in some Islamic countries to convert and become a Christian (or any thing else). It is a crime to witness to a Muslim in these Muslim countries. These laws are not new, they are simply a continuation of the teaching of Muhammad who said, "Who ever changed his Islamic religion, then kill him."
It is not just the states duty to put converts from Islam to death,it the duty of all devout Muslims to live by this rule.
Christians and Jews in Islamic lands have from the beginning been treated legally as second class citizens, called Dhimmis. Living under Dhimmitude is like living under Jim Crow on steroids, except Jim Crow has not lasted 1400 years. Dhimmis status has existed in Islamic lands for about that long.
Christians are commanded by our Lord to love Muslims. Islam is an oppressive, violent religion and Muslims suffer under it is rule. Muslims need to know the love of Christ, and we are not to hate them. We are to pray for them,do good to them and work for their conversion to Jesus Christ.