expedite vs step up

expedite

verb
  • To accelerate the progress of. 

  • To perform (a task) fast and efficiently. 

  • To perform the duties of an expediter. 

adj
  • Expeditious; quick; prompt. 

  • Free of impediment; unimpeded. 

step up

verb
  • To increase, augment, or advance, especially by one or more steps. 

  • To assume or take responsibility. 

How often have the words expedite and step up occurred in a corpus of books? (source: Google Ngram Viewer )