TERF vs terf

TERF

noun
  • A trans-exclusionary radical feminist; a radical feminist who does not consider trans women to be women, and/or thinks they should not be included in female spaces or organisations, and who considers trans men to be women. 

  • A trans-exclusionary individual, not necessarily feminist. 

terf

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