solid as a rock vs unhealthy

solid as a rock

adj
  • Extremely thick and heavy, so as to make it impossible to move. 

  • Very reliable and dependable 

unhealthy

adj
  • characterized by, or conducive to poor health 

  • characterized by disturbed mental health 

  • tending to corrupt 

  • sick or ill 

How often have the words solid as a rock and unhealthy occurred in a corpus of books? (source: Google Ngram Viewer )