Siberian vs hibernal

Siberian

adj

  • Of or relating to Siberia. 

noun

  • A person from Siberia. 

  • A long-haired domestic cat breed. 

hibernal

adj

  • Of or pertaining to winter; brumal or hiemal 

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