PEI vs Prince Edward Island

PEI

Prince Edward Island

name
  • A province in eastern Canada. Capital: Charlottetown. 

  • an island in the subantarctic Indian Ocean, part of the Prince Edward Islands, under the care and protection of South African Environmental Management 

  • An island in eastern Canada, which forms the majority of the eponymous province. 

How often have the words PEI and Prince Edward Island occurred in a corpus of books? (source: Google Ngram Viewer )