minesweeper vs sapper

minesweeper

noun
  • A vehicle, device or person with the purpose of removing explosive mines (landmines or water mines). 

  • A logic-based computer game in which the player has to discover the position of mines in a rectangular grid, based on numerical hints. 

sapper

noun
  • Historical term for a combat engineer that is still used in some armies, in other words an engineer or a soldier engaged in attacking, destroying, and circumventing or building fortifications, bridges, and roads; a military engineer active in a combat zone. 

  • An officer or private of the Royal Engineers. 

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