decrease vs taper off

decrease

verb
  • To make (a quantity) smaller. 

  • Of a quantity, to become smaller. 

noun
  • A reduction in the number of stitches, usually accomplished by suspending the stitch to be decreased from another existing stitch or by knitting it together with another stitch. See Decrease (knitting). 

  • An amount by which a quantity is decreased. 

taper off

verb
  • To diminish or lessen gradually; to become smaller, slower, quieter, etc. 

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