improve vs swallow up

improve

verb
  • To make (something) better; to increase the value or productivity (of something). 

  • To become better. 

swallow up

verb
  • To take over or absorb something (especially an organisation) so it no longer has a separate identity; to assimilate. 

  • To completely enclose or envelop. 

  • To voraciously consume resources, such as money; to devour. 

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