imperfective vs not so hot

imperfective

adj
  • Of, relating to or having the properties of the imperfective aspect. 

noun
  • The imperfective aspect; a verb having this aspect. 

not so hot

adj
  • Not very good. 

  • Used other than figuratively or idiomatically: see not, so, hot. 

How often have the words imperfective and not so hot occurred in a corpus of books? (source: Google Ngram Viewer )