impediment vs worm in the apple

impediment

noun
  • A hindrance; that which impedes or obstructs progress. 

  • Baggage, especially that of an army; impedimenta. 

  • A disability, especially one affecting the hearing or speech. 

worm in the apple

noun
  • A serious flaw in something otherwise good; a problem that ruins everything else. 

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