Which country has the oldest national anthem?

Various countries including Japan, Netherlands (Holland), and Britain lay claim to having the oldest national anthem. The Japanese anthem 'The Kimigayo (the Emperor's reign)' was adopted in 1888, and was originally a poem written by Ki No Tsurayuki in the early 10th century. The music was written in 1880. The Dutch claim is based on their anthem 'The Wilhelmus' being written in 1570, but it was not adopted as the national anthem until 1932. The British national anthem was originally a patriotic song, popular in 1745 at the time of the Scots Jacobite rebellion. The song was used thereafter to greet the British monarch whenever he/she appeared in public. The original author is unknown, and it is believed to date from the mid 16th century.

Facts:
Kimigayo (Japan): It has the oldest lyrics ever used in a national anthem. The lyrics was from a Waka Poem titled "Kokin Wakashu" first published in 905. It was officially used as a national anthem by 1999.

Wilhelmus (Netherlands): Oldest national anthem. Written and used from 1568. Making it the oldest national anthem in the world.

La Marseillaise (France): Oldest national anthem for a republic. Used as a national anthem by 1795. Lost its status under Napoleon I, and Napoleon III. Later regained it during 1879.

Lupang Hinirang (Philippines): Oldest official national anthem in Asia. Used as a national anthem by 1898. (Not so sure)

Sources:
https://en.wikipedia.org/wiki/La_Marseillaise
https://en.wikipedia.org/wiki/List_of_national_anthems
Hang, Xing (2003-09-28). Encyclopedia of National Anthems. The Scarecrow Press. ISBN 0-8108-4847-3.
Bristow, Michael Jamieson (2006-10-28). National Anthems of the World. Cassell. ISBN 0-304-36826-1.