adulthood vs the springtime of life

adulthood

noun
  • The state or condition of a human being once it has reached physical maturity, and is presumed to have reached a state of psychological maturity, to wit: once it has become an adult. 

  • The time period of a human being's majority; the time during which a human being has reached physical maturity, and ending with its death. 

the springtime of life

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