Why is it that some conservatives have this misconception that Europe is "overrun" or "taken over" by muslims?

They sure have a way of manipulating the government and starting riots and murdering people they disagree with for such a small number if you think about it. Imagine if they were the majority of the population? If that small of a number does that much damage........imagine if they were over 10% of the population? Europe would look like Iraq.