increase vs tone down

increase

verb
  • To become more nearly full; to show more of the surface; to wax. 

  • To multiply by the production of young; to be fertile, fruitful, or prolific. 

  • To make (a quantity, etc.) larger. 

  • (of a quantity, etc.) To become larger or greater. 

noun
  • The creation of one or more new stitches; see Increase (knitting). 

  • For a quantity, the act or process of becoming larger 

  • Offspring, progeny 

  • An amount by which a quantity is increased. 

tone down

verb
  • To moderate or relax; to diminish or weaken the striking characteristics of; to soften. 

  • To make a television program, piece of writing, etc. less offensive and so more suitable for a family audience. 

  • To relax; to make quieter or less obtrusive; to make milder. 

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