Back vs Grain

Back

name

  • A settlement on the Isle of Lewis, Western Isles council area, Scotland (OS grid ref NB4840). 

  • A surname. 

Grain

name

  • A village on the Isle of Grain, Medway borough, Kent, England (OS grid ref TQ8876). 

  • A surname. 

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