rishi vs sadhu

rishi

noun
  • A Hindu sage or saint occupying the same position in India history as the patriarchs of other countries, constituting a peculiar class of beings in the early mythical system, as distinct from Asuras, Devas and mortal men. 

  • A Vedic poet and seer who composed Rigvedic hymns, who alone or with others invokes the deities with poetry of a sacred character. 

sadhu

noun
  • An ascetic or practitioner of yoga (yogi) who has given up pursuit of the first three Hindu goals of life: kama (enjoyment), artha (practical objectives) and even dharma (duty). 

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