collectively vs in concert

collectively

adv
  • In a collective manner; viewed together as a whole; to be treated as a single unit, rather than the items that make up the collection separately. 

in concert

prep
  • Acting together 

  • Used other than figuratively or idiomatically: see in, concert. 

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