impaired vs lacking

impaired

adj
  • Rendered less effective. 

  • inebriated, drunk. 

noun
  • A criminal charge for driving a vehicle while impaired. 

lacking

adj
  • Missing or not having enough of (a good quality, etc). 

noun
  • The absence of something; a lack. 

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