customarily vs on average

customarily

adv
  • Under normal circumstances, normally. 

  • In the customary manner; as is custom 

on average

prep
  • Expressed as a measure of central tendency (usually the arithmetic mean). 

  • Usually, typically; as a rule; as often as not. 

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