egoism vs selfishness

egoism

noun
  • The tendency to think selfishly with exclusive self-interest in mind. 

  • Egotism (tendency to talk excessively about oneself). 

  • The belief that moral behavior should be directed toward one's self-interest only. 

selfishness

noun
  • the quality of being selfish; the condition of putting one's own interests before those of others. 

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