Chinese wolfberry vs Tibetan goji

Chinese wolfberry

noun
  • Either of two Chinese species of spiny shrub in the nightshade family, Lycium barbarum and Lycium chinense, and their edible fruits, which are used in East Asian traditional medicine. 

Tibetan goji

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