kat vs khat

kat

noun
  • An ancient Egyptian unit of weight, one fiftieth of an avoirdupois pound. 

khat

noun
  • A shrub, Catha edulis, whose leaves are used as a mild stimulant when chewed or brewed as tea; also a drug produced from this plant. 

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