air raid vs suicide bombing

air raid

noun
  • An attack on a surface target by aircraft. 

  • A passing-heavy offensive scheme based on a shotgun formation with four wide receivers and a single running back. 

suicide bombing

noun
  • An attack carried out by a suicide bomber or a group of them. 

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