babysitter vs custodian

babysitter

noun
  • A person who cares for one or more babies or children for a short period of time in place of their legal guardians. 

custodian

noun
  • A person entrusted with the custody or care of something or someone; a caretaker or keeper. 

  • a janitor; a cleaner 

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