dry spell vs slim pickings

dry spell

noun
  • A period or time where there is little activity, productivity, low income etc. 

  • A drawn-out period where the weather has been dry, for an abnormally long time; shorter and not as severe as a drought. 

  • A period of time without sexual intercourse. 

slim pickings

noun
  • A small amount, especially of money; paucity. 

How often have the words dry spell and slim pickings occurred in a corpus of books? (source: Google Ngram Viewer )