accrual vs increment

accrual

noun
  • An increase; something that accumulates, especially an amount of money that periodically accumulates for a specific purpose 

  • from the creditor's viewpoint, a charge incurred in one accounting period that has not been, but is to be, paid by the end of it. 

increment

noun
  • The amount of increase. 

  • The amount of time added to a player's clock after each move. 

  • The action of increasing or becoming greater. 

  • The waxing of the moon. 

  • An amplification without strict climax, as in the following passage: "Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report, […] think on these things." 

  • A syllable in excess of the number of the nominative singular or the second-person singular present indicative. 

verb
  • To increase by steps or by a step, especially by one. 

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