lesser vs unsustaining

lesser

noun
  • a thing that is of smaller size, value, importance etc. 

adj
  • Of two (or, rarely, more than two) things: the smaller in size (littler), in value, in importance etc. 

unsustaining

adj
  • That does not sustain. 

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