doldrums vs lack of interest

doldrums

noun
  • Usually preceded by the: a part of the ocean near the equator where calms, squalls, and light, baffling winds are common. 

  • Usually preceded by the: a state of apathy or lack of interest; a situation where one feels boredom, ennui, or tedium; a state of listlessness or malaise. 

  • Usually preceded by the: the state of a sailing ship when it is impeded by calms or light, baffling winds, and is unable to make progress. 

lack of interest

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