Chinese grapefruit vs pampelmoes

Chinese grapefruit

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

pampelmoes

noun
  • Synonym of pomelo, as both a large fruit of Southeast Asia and as a catchall term for other related fruit such as the grapefruit. 

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