assess vs plateau

assess

verb
  • To determine, estimate or judge the value of; to evaluate 

  • To impose or charge, especially as punishment for an infraction. 

  • To calculate and demand (the tax money due) from a person or entity. 

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 assess and plateau occurred in a corpus of books? (source: Google Ngram Viewer )