Wellington boots vs gumboot

Wellington boots

noun
  • Waterproof rubber boots, intended to be worn in wet or muddy conditions. Short forms: wellies (singular welly or wellie) 

gumboot

noun
  • A chiton (kind of marine mollusc). 

  • Generic black tea. 

  • A type of boot made of rubber. 

  • A style of popular music traditionally associated with gold miners. 

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