oppose vs push back

oppose

verb
  • To attempt to stop the progression of; to resist or antagonize by physical means, or by arguments, etc.; to contend against. 

  • To object to. 

  • To place in front of, or over against; to set opposite; to exhibit. 

  • To present or set up in opposition; to pose. 

push back

verb
  • To refute or argue against a position or an accusation; to express one's own view on a situation. 

  • To postpone. 

  • To summarily expel asylum seekers, especially in violation of the principle of non-refoulement. 

  • Used other than figuratively or idiomatically: see push, back. 

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