courgette vs vegetable marrow

courgette

noun
  • The edible fruit of this marrow/squash. 

  • A particular variety of Cucurbita pepo, a small marrow/squash. 

vegetable marrow

noun
  • the marrow squash 

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