SWAT vs shelling

SWAT

noun
  • A SWAT team 

shelling

noun
  • The removal of the shell from a nut, pea etc. 

  • Shallow, irregular cracks that appear on the surface of a coating such as plaster or mortar. 

  • An ordering of the facets of a boundary complex such that the intersection of each facet (other than the first) with the union of all preceding facets is homeomorphic to a ball or sphere. See Shelling (topology) 

  • An artillery bombardment. 

  • Grain from which the husk has been removed. 

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