build up vs degrade

build up

verb
  • To accumulate, to pile up, to increase in stages. 

  • To close up by building. 

  • To strengthen. 

  • In solitaire card games, to place a card over another card of lower value. (e.g., place 5♦ over 4♣) 

  • To erect; to construct. 

degrade

verb
  • To reduce in altitude or magnitude, as hills and mountains; to wear down. 

  • To lower in value or social position. 

  • To reduce in quality or purity. 

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