crofting vs sharecropping

crofting

noun
  • A form of land tenure and small-scale food production, unique to the Highlands and islands of Scotland, in which individual crofts are established on the better land while a large area of poor-quality hill ground is shared by all the crofters of the township for grazing. 

  • The process of exposing linen to the sun, on the grass, in the process of bleaching. 

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 crofting and sharecropping occurred in a corpus of books? (source: Google Ngram Viewer )