Irk vs Mole

Irk

name
  • A river in Greater Manchester, England, which joins the River Irwell in Manchester city centre. 

Mole

name
  • A river in Surrey, England, tributary to the Thames. 

  • A river in Devon, England, tributary to the Taw. 

  • A surname. 

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