bemoan vs moan

bemoan

verb
  • To moan or complain about (something). 

  • To be dismayed or worried about (someone), particularly because of their situation or what has happened to them. 

moan

verb
  • To complain; to grumble. 

  • To say in a moan, or with a moaning voice. 

  • To grieve. 

  • To make a moan or similar sound. 

noun
  • a low, mournful cry of pain, sorrow or pleasure 

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