in (a state of) limbo vs up in the air

in (a state of) limbo

up in the air

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

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

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