emission vs issuance

emission

noun
  • The act of emitting; the act of sending forth or putting into circulation. 

  • A show; a program. 

  • Something which is emitted or sent out; issue. 

issuance

noun
  • The act of issuing, or giving out. 

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