Viking vs sea rover

Viking

noun
  • A player on the Minnesota Vikings NFL team. 

  • A stock character common in the fantasy genre, namely a barbarian, generally equipped with an axe or sword and a helmet adorned with horns. 

  • A Norseman (medieval Scandinavian). 

  • An ethnic Swede, Norwegian, Dane, Icelander or Faroe Islander. 

  • Scandinavian/Northern European seafarers, most familiarly raiders and pirates during the Viking age. 

name
  • A sea area between Scotland and Norway 

  • A city in Minnesota 

  • A town in Alberta, Canada 

sea rover

noun
  • One who roams about the ocean much of the time. 

  • A pirate, buccaneer or privateer; an ocean-going marauder. 

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