introversion vs sheepishness

introversion

noun
  • A personality orientation towards the self and mental abstraction; behavior expressing such orientation. 

  • Arrangement of two similar words, lines, etc. to form the middle part of a structure. 

  • The action of turning one's thoughts upon internal or spiritual matters. 

  • A turning inward 

sheepishness

noun
  • The quality or property of being sheepish; shyness; bashfulness. 

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