asthma vs shortness of breath

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. 

shortness of breath

noun
  • difficulty in breathing; dyspnea 

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