bogle vs kobold

bogle

noun
  • A goblin; a frightful spectre or phantom; a bogy or bugbear. 

kobold

noun
  • A mischievous elf or goblin, or one connected (and helpful) to a family or household. 

  • One of a diminutive and usually malevolent race of beings. 

  • An ambivalent, sometimes vindictive, spirit that is capable of materialising as an object or human, often a child; a sprite. 

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