foster care vs rearing

foster care

noun
  • A formal system by which a child is cared for, in a foster family, by people other than its own parents, but without being adopted. 

rearing

noun
  • Act of raising young. 

  • We studied blowfly rearings in various environmental conditions. 

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