inconclusive vs up in the air

inconclusive

adj
  • Not conclusive, not leading to a conclusion. 

up in the air

adj
  • Not yet resolved, finished, answered, decided or certain. 

adv
  • Used other than figuratively or idiomatically: see up, in, the, air. 

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