lame duck vs mollusc

lame duck

noun
  • A person or thing that is helpless, inefficient, or disabled. 

  • An elected official who has lost the recent election or is not eligible for reelection and is marking time until leaving office. 

mollusc

noun
  • A weak-willed person. 

  • A soft-bodied invertebrate of the phylum Mollusca, typically with a hard shell of one or more pieces. 

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