bootlicker vs lap dog

bootlicker

noun
  • A person who behaves in a servile or obsequious manner; a toady 

  • Anyone who is seen as supporting authoritarianism. 

lap dog

noun
  • A person who behaves in a servile manner, such as a sycophantic employee or a fawning lover. 

  • A small toy dog, kept as household pet, whose light weight and companionable temperament make it both suited and disposed to spend time resting in the comfort of its master's lap; a dog bred to behave in this manner. 

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