belt-tightening vs mitigation

belt-tightening

noun
  • A reduction in expenditure, often as a result of financial restrictions. 

adj
  • Causing or involving a reduction in expenditure. 

mitigation

noun
  • A reduction or decrease of something harmful or unpleasant. 

How often have the words belt-tightening and mitigation occurred in a corpus of books? (source: Google Ngram Viewer )