in round numbers vs thereabouts

in round numbers

thereabouts

noun

  • Location; whereabouts. 

adv

  • About or around that date or time. 

  • Approximately that number or quantity. 

  • About or near that place. 

  • About or near to that condition or quality. 

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