confess vs let cat out of the bag

confess

verb
  • To hear or receive such a confession of sins from. 

  • To acknowledge faith in; to profess belief in. 

  • To unburden (oneself) of sins to God or a priest, in order to receive absolution. 

  • To disclose or reveal. 

  • To admit to the truth, particularly in the context of sins or crimes committed. 

let cat out of the bag

How often have the words confess and let cat out of the bag occurred in a corpus of books? (source: Google Ngram Viewer )