leading vs top-priority

leading

adj
  • Ranking first. 

  • Providing guidance or direction. 

  • Occurring in advance; preceding. 

noun
  • Vertical space added between lines; line spacing. 

  • An act by which one is led or guided. 

top-priority

adj
  • Of the highest level of importance 

  • To be done before doing anything else. 

How often have the words leading and top-priority occurred in a corpus of books? (source: Google Ngram Viewer )