Chinese grapefruit vs pomelo

Chinese grapefruit

noun

  • Synonym of pomelo (“SE-Asian citrus fruit”) 

pomelo

noun

  • The large fruit of the Citrus maxima (syn. C. grandis), native to South Asia and Southeast Asia, with a thick green or yellow rind, a thick white pith, and semi-sweet translucent pale flesh. 

  • The tree which produces this fruit. 

  • the grapefruit. 

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