groundskeeping vs sharecropping

groundskeeping

noun
  • The activity of tending an area of land for aesthetic or functional purposes; typically as an employee of a person or institution 

sharecropping

noun
  • The system where a tenant farmer, especially in the southern United States, farms the land in exchange for a portion of the crops. 

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