pusillanimity vs unassertiveness

pusillanimity

noun
  • The quality or state of being pusillanimous; the vice of being timid and cowardly, and thus not living up to one's full potential; pusillanimousness. 

unassertiveness

noun
  • The state or condition of being unassertive. 

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