Burden vs Riddle

Burden

name
  • A minor city in Cowley County, Kansas, United States. 

  • A surname. 

  • A village in Erpeldange commune, Luxembourg (French spelling). 

Riddle

name
  • A city in Douglas County, Oregon, United States. 

  • A surname. 

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