escalate vs plateau

escalate

verb
  • To increase (something) in extent or intensity; to intensify or step up. 

  • To climb. 

  • In technical support, to transfer a customer, a problem, etc. to the next higher level of authority 

plateau

verb
  • (of a varying quantity) To reach a stable level after a period of increase; to level off. 

noun
  • A comparatively stable level after a period of increase. 

  • A notable level of attainment or achievement. 

  • A largely level expanse of land at a high elevation; tableland. 

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