close in vs pen in

close in

verb
  • To enclose, lock up inside something. 

  • To come nearer to someone being pursued. 

pen in

verb
  • To enclose (animals) in a pen. 

  • To schedule; fix a date for. 

  • To cause to be stuck in a situation; to be forced into a situation by circumstances. 

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