cat thyme vs kitty crack

cat thyme

noun
  • A low-growing herb, Teucrium marum, related to germander, which has a pungent scent that causes sneezing, but is attractive to cats. 

kitty crack

noun
  • cat thyme (Teucrium marum) 

How often have the words cat thyme and kitty crack occurred in a corpus of books? (source: Google Ngram Viewer )