shudder vs titubate

shudder

verb
  • To vibrate jerkily. 

  • To shake nervously, often from fear or horror. 

noun
  • A moment of almost pleasurable fear; a frisson. 

  • A shivering tremor, often from fear or horror. 

titubate

verb
  • To stutter, stammer. 

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