common bean vs string bean

common bean

noun
  • An herbaceous annual plant (Phaseolus vulgaris), grown for its edible bean. 

  • A bean of such a plant, varying in size, shape and especially color. 

string bean

noun
  • A common bean (Phaseolus vulgaris) 

  • A hyacinth bean (Lablab purpureus) 

  • Any long, slender green bean. 

  • A tall and thin person. 

  • An immature runner bean (Phaseolus coccineus) 

  • A yardlong bean (Vigna unguiculata subsp. sesquipedalis) 

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