heavy goods vehicle vs semi-trailer truck

heavy goods vehicle

noun
  • A lorry, truck or other large vehicle used to transport cargo with a total weight of at least 3.5 tonnes. 

semi-trailer truck

noun
  • A tractor-trailer or big rig, consisting of a semi-trailer and a semitruck pulling it. 

How often have the words heavy goods vehicle and semi-trailer truck occurred in a corpus of books? (source: Google Ngram Viewer )