belt-tightening vs diminishing

belt-tightening

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

adj
  • Causing or involving a reduction in expenditure. 

diminishing

noun
  • A diminishment. 

adj
  • becoming smaller 

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