oakwood vs softwood

oakwood

noun
  • A wood populated with oak trees. 

softwood

noun
  • The tree or tree species that yields this wood. 

  • Any commercial timber. 

  • The wood from any gymnosperm, without regard to how soft this wood is. 

  • Wood of this kind, but limited to those that are commercial timbers. 

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