Sister vs clerical

Sister

noun
  • Title of respect for an adult female member of a fraternal/sororal organization, or comrade in a movement, or even a stranger using fictive kin. 

  • A title used to personify or respectfully refer to concepts or animals. 

  • Title of respect for an adult female member of a religious order. 

clerical

noun
  • Clerical garments. 

  • A member of the clergy. 

adj
  • Of or relating to the clergy. 

  • Of or relating to clerks or their work. 

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