Keystone vs Leader

Keystone

name
  • A census-designated place in Colorado. 

  • A city and town in Iowa. 

  • A town in South Dakota. 

  • A ghost town in North Dakota. 

Leader

name
  • A locality in Adams County, Colorado, United States. 

  • A town in the Rural Municipality of Happyland No. 231, western Saskatchewan, Canada, originally named Prussia. 

  • A river in north Canterbury, New Zealand, which joins the (Canterbury) Waiau. 

  • A surname originating as an occupation for a person who led a horse and cart. 

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