a bolt from the blue vs bombshell

a bolt from the blue

bombshell

noun
  • A bomb or artillery shell designed to explode on impact. 

  • Something that is very surprising, shocking, amazing or sensational. 

  • Someone who is very attractive; a sex symbol. 

How often have the words a bolt from the blue and bombshell occurred in a corpus of books? (source: Google Ngram Viewer )