adverse possession vs squatting

adverse possession

noun
  • A means of acquiring title to another's real property without compensation by occupying the property in a manner that has under common law the requirements of being actual, open and notorious, exclusive, hostile, under cover of claim or right, and continuous for a certain number of years. 

squatting

noun
  • The act or general practice of occupying a building or land without the permission of the owner. 

  • The posture of one who squats. 

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