Casper vs Kaspar

Casper

noun
  • A white person. 

name
  • A city, the county seat of Natrona County, Wyoming, United States 

  • A male given name from Old Persian, of occasional usage, variant of Caspar. 

  • A mountain in Wyoming 

Kaspar

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