VD vs scabies

VD

noun
  • The design diving speed of an aircraft; the highest speed which the aircraft is planned to reach during flight testing. Always higher than VNE (the speed that must not be exceeded in service). 

scabies

noun
  • An infestation of parasitic mites, Sarcoptes scabiei, causing intense itching caused by the mites burrowing into the skin of humans and other animals. It is easily transmissible from human to human; secondary skin infection may occur. 

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