suit of armor vs suit of armour

suit of armor

noun

  • A collection of garments, usually made of metal, worn over the body for protection in battle from weapons. 

suit of armour

noun

  • A collection of garments, usually made of metal, worn over the body for protection in battle from weapons. 

How often have the words suit of armor and suit of armour occurred in a corpus of books? (source: Google Ngram Viewer )