Br vs bromine

Br

noun
  • Belarusian. 

adj
  • Belarusian. 

bromine

noun
  • A bromine atom 

  • A nonmetallic chemical element (symbol Br) with an atomic number of 35; one of the halogens, it is a fuming red-brown liquid at room temperature. 

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