present imperfect vs preterite

present imperfect

noun
  • A grammatical tense which presents the action in the present as continuous, not yet over 

preterite

noun
  • A grammatical tense or verb form serving to denote events that took place or were completed in the past. 

adj
  • Belonging wholly to the past; passed by. 

  • showing an action at a determined moment in the past. 

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