swap out vs trade in

swap out

verb
  • To exchange (something or someone) for an unused (or less-used) equivalent. 

  • To exchange (something) for (something else). (usually followed by with or for) 

  • To transfer (memory contents) into a swap file. 

noun
  • Anything that is swapped out for another; an exchange. 

  • A pre-prepared food item used in place of an unfinished food item in order to cut down the overall preparation time during filming. 

trade in

verb
  • To give a piece of merchandise as part of the payment or trade for something new. 

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