dipped headlight vs headlamp

dipped headlight

noun
  • The main light on a motor vehicle, with the beam in a lower angle position, to enable oncoming traffic to see. 

headlamp

noun
  • An individual headlight, particularly of a motor vehicle. 

  • A flashlight worn on the head. 

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