preadolescence vs schooldays

preadolescence

noun
  • The period between childhood and adolescence, between the ages of about 9 and 11 for girls, and 10 and 12 for boys. 

schooldays

noun
  • The period of one's life when one attends school, particularly, primary school (as opposed to college days); one's youth. 

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