pep vs zeal

pep

noun
  • Energy, high spirits. 

verb
  • To inject with energy and enthusiasm. 

zeal

noun
  • The fervour or tireless devotion for a person, cause, or ideal and determination in its furtherance; diligent enthusiasm; powerful interest. 

  • The collective noun for a group of zebras. 

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