emergency service vs trauma centre

emergency service

noun
  • Any public service that deals with emergencies; especially the police, fire, ambulance, or lifeboat services. 

trauma centre

noun
  • A specialized section of a hospital intended to treat suddenly occurring life-threatening injuries and medical conditions. 

  • A type of hospital with a highly capable trauma department. 

How often have the words emergency service and trauma centre occurred in a corpus of books? (source: Google Ngram Viewer )