ast Wednesday was a National Holiday in the Netherlands "Kings Day". The coming week the Dutch will commemorate the remembrance (May 4) and end of WWII (May 5). These are the days when the National Anthem is sung.
Trivia: "The Wilhelmus" is the oldest known national anthem in the world! It has 15 stanzas and it is acrostic. It was written in the 16 century during the battle between the Spanish Catholic Soldiers and the Protestants in the 'Low Countries'.