inflate vs let down

inflate

verb
  • To decompress (data) that was previously deflated. 

  • To enlarge an object by pushing air (or a gas) into it; to raise or expand abnormally 

  • To swell; to puff up. 

  • To enlarge by filling with air (or a gas). 

let down

verb
  • To disappoint; to betray or fail somebody 

  • To reduce one's level of effort. 

  • To soften in tempering. 

  • Used other than figuratively or idiomatically: see let, down. 

  • To allow to descend. 

  • To lengthen by undoing and resewing a hem. 

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