breathlessness vs labored breathing

breathlessness

noun
  • The state of being breathless or out of breath. 

  • Difficult or labored respiration, dyspnea, shortness of breath 

labored breathing

noun
  • Breathing at less than 12 or more than 20 breaths per minute with poor or irregular quality, rhythm, or tidal volume; a sign of respiratory distress. 

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