loosen up vs luxuriate

loosen up

verb
  • To relax; to act less seriously. 

  • To become loose; to loosen; to relax (a muscle, etc.). 

luxuriate

verb
  • To enjoy luxury, to indulge. 

  • To be luxuriant; to grow exuberantly. 

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