avert vs speed up

avert

verb
  • To ward off, or prevent, the occurrence or effects of. 

  • To turn aside or away. 

speed up

verb
  • To increase the speed of something; to make something go faster. 

  • To accelerate; to increase speed. 

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