account for vs underestimate

account for

verb
  • To destroy or put out of action. 

  • To make or render a reckoning of funds, persons, or things. 

  • To be answerable for. 

  • To be the primary cause of 

  • To explain by relating circumstances; to show that some one, thing or members of a group are present or have been processed. 

  • To constitute in amount or portion. 

underestimate

noun
  • An estimate that is too low. 

verb
  • To perceive (someone or something) as having a lower value, quantity, worth, etc., than what he/she/it actually has. 

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