chard vs potato salad

chard

noun
  • An edible leafy vegetable, Beta vulgaris subsp. cicla, with a slightly bitter taste. 

  • Artichoke leaves and shoots, blanched to eat. 

potato salad

noun
  • A salad made from chopped boiled potatoes and a variety of other ingredients in a dressing. 

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