knee-high to a grasshopper vs lastborn

knee-high to a grasshopper

adj
  • short; especially relating to when the subject was a small child 

lastborn

adj
  • Born last in a family; youngest in a the family. 

  • Younger than anyone else in a group. 

noun
  • The youngest child of a family. 

  • The youngest member of any company or organization. 

How often have the words knee-high to a grasshopper and lastborn occurred in a corpus of books? (source: Google Ngram Viewer )