altruism vs unselfishness

altruism

noun
  • Regard for others, both natural and moral without regard for oneself; devotion to the interests of others; brotherly kindness. 

  • Action or behaviour that benefits another or others at some cost to the performer. 

unselfishness

noun
  • The state of being unselfish. 

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