needling vs smouldering

needling

noun
  • The act of one who needles or annoys. 

  • A needy person. 

smouldering

noun
  • The act by which something smoulders; residual heat. 

adj
  • Burning slowly, producing smoke but no flame. 

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