A trivia question for you: what national anthem has no official words? Hint: they were deleted after someone's death in 1975. Answer below the fold:
Spain. "La Marcha Real is the only national anthem with no official words. They were dropped in 1975, on the death of General Franco, with whom they were associated strongly in the public’s mind."
Addendum: An anonymous reader has pointed out that "Europe," the national anthem of Kosovo also has no lyrics (in order not to favor any ethnic group).