seven vs seven-spot

seven

num
  • A numerical value equal to 7; the number following six and preceding eight. This many dots: (•••••••). Describing a group or set with seven elements. 

noun
  • The digit/figure 7 or an occurrence thereof. 

  • A card bearing seven pips. 

seven-spot

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