sit down vs spring up

sit down

verb
  • To assume a low or sunken position. 

  • To meet formally at a conference table. 

  • To cause to be seated or in a sitting posture; to furnish a seat to. 

  • To assume a sitting position from a standing position. 

spring up

verb
  • To appear suddenly. 

  • To come rapidly into existence. 

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