formication vs paresthesia

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. 

paresthesia

noun
  • A sensation of burning, prickling, itching, or tingling of the skin, with no obvious cause. 

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