herbal tea vs manuka

herbal tea

noun
  • A beverage made by infusing the leaves of various herbs, generally not including true tea (Camellia sinensis). 

manuka

noun
  • The wood of this plant. 

  • Leptospermum scoparium, a shrub or small tree native to New Zealand and southeast Australia. 

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