Saptarishi vs Wagon

Saptarishi

Wagon

name
  • A bright circumpolar asterism of the northern sky, said to resemble a ladle or cart. It is part of the constellation Ursa Major and includes the stars Mizar, Dubhe, and Alkaid. 

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