bad part of town vs rookery

bad part of town

noun
  • A dilapidated area of a city where many people live in a state of poverty and in which crime is more common than in other portions of the city. 

rookery

noun
  • A place where criminals congregate, often an area of a town or city. 

  • A colony of breeding birds or other animals. 

  • A crowded tenement. 

How often have the words bad part of town and rookery occurred in a corpus of books? (source: Google Ngram Viewer )