goji vs wolfberry

goji

noun
  • A fruit in the genus Lycium, especially in commercial products where it is promoted as a superfruit. 

wolfberry

noun
  • Any of flowering species of the genus Lycium. 

  • Lycium barbarum or Lycium chinense 

  • The berry of this plant. 

  • The western snowberry, Symphoricarpos occidentalis, a shrub native to nothern and central North America. 

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