Berg vs Slough

Berg

name
  • A former duchy and later grand duchy in Westphalia (Western Germany). 

  • A municipality of Troms, Norway. 

  • A surname from German common in the US, associated with German or Scandinavian ancestry. 

Slough

name
  • A borough and unitary authority (Slough Borough Council) in Berkshire. 

  • A town in east Berkshire, England (formerly Buckinghamshire), close to Heathrow Airport. 

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