hegumen vs parson

hegumen

noun
  • The head of a monastery of the Eastern Orthodox Church or Eastern Catholic Churches. 

parson

noun
  • A Roman Catholic priest of an independent parish church. 

  • A Protestant minister. 

  • An Anglican cleric having full legal control of a parish under ecclesiastical law; a rector. 

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