4.4% in '98, it'll be a bit more now but not all that much. (contrary to common belief, immigration in the past few years hasn't been all that huge)
http://www.worldfactsandfigures.com/...etherlands.php
Religions: Roman Catholic 31%, Protestant 21%, Muslim 4.4%, other 3.6%, unaffiliated 40% (1998)
You should remember that the Netherlands isn't just Amsterdam, Rotterdam, The Hague and Utrecht.