repress vs step on

repress

verb
  • To check; to keep back. 

  • To press again. 

  • To forcefully prevent an upheaval from developing further. 

noun
  • A record pressed again; a repressing. 

step on

verb
  • Used other than figuratively or idiomatically: see step, on. 

  • to adulterate a drug for the purpose of increasing its bulk, and therefore its profit; to dilute, cut. 

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