anxiety vs formication

anxiety

noun
  • An unpleasant state of mental uneasiness, nervousness, apprehension and obsession or concern about some uncertain event. 

  • An uneasy or distressing desire (for something). 

  • A state of restlessness and agitation, often accompanied by a distressing sense of oppression or tightness in the stomach. 

formication

noun
  • An abnormal skin sensation similar to that of insects crawling over or within the skin; a tactile hallucination involving such a sensation. A common side-effect of substance abuse, it can also be experienced with high fever, menopause, skin cancer, diabetic neuropathy, or herpes zoster. 

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