mentally retarded vs thick as champ

mentally retarded

adj
  • intellectually disabled, medically defined as having an IQ (intelligence quotient) below 70 in addition to deficits in two or more adaptive behaviors (which means having problems with basic functional skills that affect everyday, general living). 

thick as champ

adj
  • Very ignorant or foolish, sullen or in a bad temper. 

How often have the words mentally retarded and thick as champ occurred in a corpus of books? (source: Google Ngram Viewer )