crucial vs leading

crucial

adj
  • Essential or decisive for determining the outcome or future of something; extremely important; vital. 

  • Very good; excellent; particularly applied to reggae music. 

leading

adj
  • Occurring in advance; preceding. 

  • Providing guidance or direction. 

  • Ranking first. 

noun
  • Vertical space added between lines; line spacing. 

  • An act by which one is led or guided. 

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