asthma vs breathlessness

asthma

noun
  • A long-term respiratory condition, in which the airways may unexpectedly and suddenly narrow, often in response to an allergen, cold air, exercise, or emotional stress. Symptoms include wheezing, shortness of breath, chest tightness, and coughing. 

breathlessness

noun
  • Difficult or labored respiration, dyspnea, shortness of breath 

  • The state of being breathless or out of breath. 

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