devotion vs fervency

devotion

noun
  • The act or state of devoting or being devoted. 

  • Feeling of strong or fervent affection; dedication 

  • Religious veneration, zeal, or piety. 

  • A prayer (often found in the plural) 

fervency

noun
  • The state of being fervent. 

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